Lemme is an abreviation of "let me". Although used mostly in text, this vocal verbatim is a key component of the language of modern youths. Since the pronounciation of "let me" requires too many syllables, lemme has become an accepted form of expressing this action.
lemme call you back.
Short for "let me". Not discovered by this person. Actually renowned everywhere. When some people say let me, it comes out as "lemme" instead.
Hey, "lemme" pay you back tomorrow, OK?
Short for "let me". Was discovered by accident as a joke by me some months ago. Or has it been a year? Eh, whenever.
Hey lemme call u back since I need to figure out if i can afford that vid card for u, aight?