M4htm4gh4nd1, or, mahatma ghandi, is a term given to the name of someone that you have forgot the name of momentarily instead of whatshisname in l33t. It is also given to someone who is being highly cool at one moment.
Bob: h3y, sup. U g0in' to m4h4tm4g4nd1's pl4c3 2day?
Fred: U mean Sam's?
Bob: I just jumped all those O.A.Ps on mi motorbike!
Fred: Yeye! U m4h4tm4gh4nd1!!!!!!111!!!!