The state of sudden excitement and euphoria a person is in when at a party, or when a party is possible. Party boners can make normally calm individuals unpredictable.
1. Person 1: Whoa, Dan is starting to strip in the corner.
Person 2: Yeah man, Dan has a massive party boner.
2. Person 1: Everbody's going to the party at Dave's house!
Person 2: Party at Dave's house?! I SO just popped a party boner.