1995 Nissan Altima Tail lights stay on

Well if the light switch is off and foot is off the brake and the keys are out, then you have a short to power. This will be a game of hide and seek. I would start at the tail lights and work your way forward following the wires. Look for anything burned or smashed. The problem will likely be near the front of the car near where the wires for the tail lights split from one wire to two wires. Some systems branch off right in the back under the trunk carpet. Next check the brake switch, attached to the brake peddal, by disonnecting it and checking if lights go out. If you still have not found the problem start checking any set of wires you can find for problems.