Strangest thing happened to my car recently.
'99 Hyundai Accent, last week I had to replace one of my tail light bulbs, which I did. Now, when I step on the brake pedal, my dash lights go on!! WTF?
Any ideas why this might have happened and how I can fix it?
H.
It’s not good form to make the obvious joke before any serious posts, so I’ll have to wait. 
Check to see if you put a 1-terminal bulb in a 2-terminal socket (or vice versa). 90% chance that’s it.
I guess I agree with Gary T. It seems vaguely reasonable that the tail lights (as opposed to brake lights) and dash lights could be on the same circuit as they both go on when you turn on the headlights. So if you were somehow connecting the positive voltage to the tail lights when you applied the brake pedal, then you might also light up the dash lights. And I guess the wrong bulb, or a mis-aligned bulb might possibly allow that to happen. Depending on how shoddy the connectors are (and I’ve seen some fairly shady ones in cars), it could also be that one of the connecting wires got dislocated while you were changing the bulb.
Better possessed than repossessed.
(Sorry; I lack AskNott’s self-control.)