Mikey set his alarm so that he would wake up around three in the morning. This way, Jon was deep into sleep and Mikey would have less of a chance at waking him up.
After waking, Mikey snuck into his brother's room and snatched the stone. Fortunately, it was sitting on his nightstand, so it was easy to find.
When he got back to his bedroom, he sat on his bed, looking at the stone. Then, after he took a moment to think, he said "I wish ..."