In childhood he was made fun of and called the gaper - or 'open mouthed'. He was unattractive - so not like the actor Maximilian Schell who portrayed the saint in the bio-pic, The Reluctant Saint. In fact, he was pretty much considered good for nothing - yet he was favored with many mystical graces and rapt in 'the mystery of devotion' throughout his life.
I often think of him when recalling kids I knew in school, kids who were bullied because the were different, unattractive and slow. I pray for them now, but as a kid I made fun of them at times as well. We didn't know about autism as kids, but at least two classmates of mine demonstrated the same characteristics as St. Joseph Cupertino. I found a piece written about him on Aleteia, which I'll share.
One of three saints who may have had autism.
Throughout his life, Joseph was highly misunderstood and ridiculed by everyone. His frequent visions and sudden outbursts of anger made him an object of mockery. Additionally, Joseph was very absent-minded, awkward and extremely sensitive to his surroundings. When the school bell rang, Joseph would jump and drop his books on the ground.
In school, Joseph earned the nickname “open-mouthed” because his mouth was always open. He could barely read or keep focus and often would forget to eat his meals. However, even though he barely progressed in education Joseph didn’t seem to mind or notice and sought to gain entrance into a monastery despite this deficiency. Joseph figured that at least he could beg for bread as a Franciscan.
This also did not go well for Joseph. The community did not understand him and his inability to complete simple tasks without breaking something, and the experiment proved too difficult to handle. He was expelled from the monastery, but with nowhere to turn, Joseph came back and begged the community to at least hire him as a servant. The Franciscans consented, enrolled him in the Third Order and assigned him the task of taking care of the monastery mule.
Joseph’s joyful demeanor was infectious and over time they gave him a second chance and allowed him into the community. Joseph was eventually ordained a priest and is most famous for his ability to levitate while saying Mass (they tied a rope around his leg so that he wouldn’t fly into the ceiling). Despite his lack of education, awkwardness in social situations and inability to complete basic tasks, Joseph was widely known for his extreme piety, simplicity and humility. - Aleteia
It was not 'his' ability to levitate while saying Mass.
I'd also like to include some solid mystical theology regarding supernatural graces such as levitation. It is a grace, a charism-gift, not an ability, the saints have no control over it. Many people today discount these accounts, which were well documented by eye witnesses in the case of St. Joseph, and other saints such as the Discalced Carmelite, St. Mary of Jesus Crucified, The Little Arab.
By levitation is understood the phenomenon of the elevation of the human body above the ground without any apparent cause and in such a way that it remains in the air without any natural support. This phenomenon is also called ascensional ecstasy, ecstatic flight, or ecstatic walking when the body seems to run rapidly without touching the ground.
The Bollandists relate numerous cases of levitation. They cite particularly those attested in the lives of St. Joseph of Cupertino (September 18), St. Philip Neri (May 26), St. Peter of Alcantara (OctoBer 19), St. Francis Xavier (December 3), St. Stephen of Hungary (September 2), St. Paul of the Cross (April 28), and others. It is related that St. Joseph of Cupertino, seeing some workmen having trouble in trying to put up a very heavy mission cross, took his aerial flight, seized the cross, and without effort placed it in the hole destined for it.
In contradistinction to levitation, they cite cases of extraordinary weight of the bodies of certain saints: for example, when an attempt was made to violate and drag St. Lucy of Syracuse to a place of debauchery, her body remained fixed to the earth like the pillar of a church.
Suggestion or autosuggestion of hysterical persons has never been able to provoke levitation. After an examination extending over several years, Professor Janet of Paris was able to establish that the body of the person was never raised, even a millimeter, even sufficiently to slip a cigarette paper between his feet and the ground.(21)
Rationalists have tried to explain naturally the levitation proved in the case of several saints by the deep breathing of air into the lungs; but, in the face of the manifest insufficiency of this reason, they have had to have recourse to an unknown psychic power an explanation that is merely so many words.
Benedict XIV states the traditional and reasonable explanation.(22) He requires first of all that the fact be well proved in order to avoid all trickery. Then he shows: (I) that because of the law of gravity, well-proved levitation cannot be naturally explained; (2) that it does not, however, exceed the powers of angels and the devil, who can lift bodies up; (3) that consequently the physical, moral, and religious circumstances of the fact must be carefully examined to see whether there is not diabolical intervention; and that, when the circumstances are favorable, one can and must see in it a divine or angelic intervention, which grants to the bodies of the saints an anticipation of the gift of agility which is proper to glorified bodies. - Garrigou-Lagrange
St. Joseph Cupertino, pray for us.