here's how it goes.

one person wishes for something they want. the next person then grants that wish, and then states a consequence. example:

"person A: i wish i was rich and famous."
"person B: wish granted, but now you're hooked on crack and on the dole. i wish i had a trillion dollars."
"person C: wish granted. ten seconds later, a trillion dollars in coin falls out of your ceiling and crushes you. i wish for.."

i wish i had a tricycle.