A bad question is one that is bad, awkward, or otherwise full of cheese. They often occur in the presence of journalism or relationships. They taste kind of like lemons but I've never tried eating one.
Or maybe grapefruits. But presumably something bad.
An example of a bad question is: When did you go to bed last night? or What were you doing last night anyway? This is because you were probably playing with invisible cats, and now your mom hates you because invisible cats go contrary to the principles of the One True Fosterite Faith, and we have to kill all the sinners by throwing tomatoes at them. Tomatoes filled with pooop and launched from a Death Star, and you will feel a great disturbance in the Force but nobody will hear your screams because Darth Vader is busy vacuuming the air off your planet.
This means you will probably die. But you were going to do that anyway, so what's the rush? Seriously. Quit your whining.