A question that includes a guess or assumption in it.
The following ARE Guestions:
"There's about 5000 jellybeans in that jar wouldnt you say?"
"You've got a laptop in that bag dont you?"
"You probably just got dumped, thats why ya look so sad isnt it?
The following are NOT Guestions:
"How many jellybeans do you think are in that jar?"
"What do you have in that bag?"
"Why do you look so sad?"
Answering to a question which you are unsure about in a questioning way.
Greg: "Hey, Dave do you know the capital of China?"
Greg: "Are you sure or is that a guestion?"
A question, asked when someone knows that something's up, but they're not sure what, and so guess at anything, and ask that.
"Omg Dave, you've got a girlfriend?"
"Now you're just asking guestions."