What does the slang term doughface mean?

It basically means, your face is made of dough, either because you're a jerk, idiot, or generally clueless.

It could be used in this situation:

"Give me back my hairband!" Said 5 year old Lucy,

"No chance!" Said her twin Brian,

"MUUUUUUUM!" Lucy shouted,

"You're such a doughface, running to mum all the time, it was only a joke," Brian scoffed.