Don't Pump My Grundle

The act of raising somebody's hopes with an erroneous claim that makes the speaker look foolish. This claim is made with good intentions but is so faulty that it utterly fails to affect the general mood positively. In many cases the result of pumping somebody's grundle is negative.

Ex1:
LeRoy: Aw shit, that shorty over there, she's fine as hell. I'd hit that like a piñata on cinco de mayo!

Marcus: She's FUGLY homey, don't pump my grundle, she's just nasty...