dopey dickin

When a friend screws you out of money on the sly.

Ex. If your friend is supposed to put a bet in for a game for you and then when your team wins, he calls you up and says "I forgot to put the bet in".

Ex. He's running a football pool and the pools rules change week to week benefitting his picks.

"Hey Harry, did you collect from
Mack? I heard you won. Congrats"!
"No. Mack never ended up putting the bet in. He forgot".
"Ah man. That Mack is dopey dickin. You can't trust him"
"Yeah, he's a real snake in the grass"