Getting slightly intoxicated before going outside of your residence to drink with your friends in public. Commonly practiced by poorer or more frugal individuals who still want to go out and have a good time.
"I only have ten dollars for drinks for the whole night so I have to get predrunk at Dave's before we went out to the clubbbb to get for realz drunk."
When you are drunk before you go out
We were going to the club but I was too predrunk to get in