If somebody asks you to do something, and you think this is too ridiculous or simply impossible to do, you can give one of the following answers. They all mean more or less “No way!” or “Forget it”.

Ja, da–ag!

Yes, goodbye = no, forget it

Dacht ’t niet!

didn’t think so = won’t happen

Vergeet ’t maar

Just forget it = not gonna happen

Geen denken aan

I won’t even think about it

Ik pieker er niet over

I won’t even consider it

Kom nou!

Oh come on

Ben je helemaal belatafeld?

Are you crazy??

What does belatafeld mean?

tafel = table

la = drawer

be-la-tafel-d =>  to be table-drawered ? ??

Well. It actually doesn’t mean that.
It is only a way of saying…that you must be out of your mind