IDHM 

Abbreviation for "I DONT HAVE MONEY" very common used in Messenger

Bryan: dude ya going to the party
andy: No dude IDHM for gas :l

IDHM by MLB_Prospect May 14, 2011

IDHMBWM 

I Don't Have My Books With Me

"I think it's explained on pages 13-15 but I'm not sure because IDHMBWM."

IDHMBWM by xomba June 15, 2008