Warning: contains spoilers for What If...? Miles Morales Became The Hulk? #1!
Marvel's new Miles' transformation into the famous Incredible Hulk is, oddly enough, his most relatable.
In the first issue in the series, Miles Morales became Captain America in an alternate universe in which Miles lived on a military base with his family. When he accidentally drank the Super-Soldier Serum (and inadvertently stopped his Uncle Aaron's attempt to steal it for himself), he was trained in the same manner as Steve Rogers in the 616 universe. In the subsequent issue, Miles is a mutant who was experimented on in the same manner as Wolverine; he becomes Wolverine and is eventually met by Professor X years later - here seen as his childhood friend Ganke. Now Miles undergoes his strangest transformation yet.
In What If...? Miles Morales Became The Hulk? #1, written by Anthony Piper with art by Edgar Salazar, Miles steps on a pellet of concentrated gamma energy stolen by Aaron - after, ironically enough, attempting to kill a spider ("I absolutely hate spiders" he mentions to his therapist). This triggers a transformation that occurs at night (similar to the original Grey Hulk), frightening Miles. He refuses to tell his parents and confesses to Ganke instead, who doesn't believe him in the slightest - until Miles steps on a LEGO brick barefoot, causing tremendous pain and instantly triggering an anger-induced transformation.
LEGO bricks are made of incredibly hard plastic with sharp edges and they rarely break under stress - unlike Miles. His transformations are not just triggered by anger, but by guilt as well. When Miles sees his Uncle Aaron killed by the Abomination, Miles immediately transforms and beats the monster to death. In his therapists' office, he transforms again once he accepts that the anger was a byproduct of his comion.
Note that Miles never causes massive destruction and property damage in the issue (unlike Bruce Banner, who can't control the Hulk and routinely demolishes buildings when angry). Miles is instead angry at the little things in life - such as a woman rejecting his request to study for a test in school, or stepping on a LEGO brick. Miles Morales may not have become the Hulk in the main universe, but he's always looking out for others - even if he has to endure the pain of stepping on a LEGO to do so.
