"I Stamp" is a DMV phrase used to officiate ones claims. If you tell someone a story and they don't believe you then you've gotta stamp it, that it really happened! Then they will ask you "on who' did what you said happened. The only response you can give to make someone believe you is "On Movas"!!! You've gotta stamp it on movas to let them know you are serious! It's just the way it goes in the DMV. A play on the IHOP logo.