sneakin m&ms 

when you have hard nipples, as if you were hiding m&m's in your shirt.

It was cold out, so i asked Nick if he was sneakin M&ms.

sneakin m&ms by Justin To January 3, 2008

sneaking m&ms 

A slang term for a woman or man with notecably erect nipples as if sneaking M&Ms

did you see that girl sneaking m&ms? it must be really cold outside

sneaking m&ms by Pinoythespian March 28, 2005