Rax is a slang word for the words bust, leave, grab, blowing your load, steal, pass, go to, get to, begin.
When you hear it in a sentance you need to listen carefully afterwards to see the context it was used in and apply the proper word.
Yo let's rax some flower.
Did you see how fast Smith raxed after he saw Jodie rax in to the room. He should have raxed in her hair.
Ive gotta rax some work dude.... if i dont talk to you... have a sick drive to school - don't rax anything until i get there.