Avril Lavigne hosted Prive Night club at the Planet Hollywood Casino in Las Vegas on New Years Eve. Lil John was also in attendance as a guest DJ. According to Page Six, Avril got really pissed because Lil John was stealing all her thunder. She was reportedly set to do the count down when onlookers saw 'Lil Jon "grab his own mike and steal the show."

Apparently, she got really pissed and started crying saying "I wanted to do the count down."

We were at Prive on New Years Eve as well and Lil John did definitely steal Avril's thunder away. She was not such a good host! We didn't even know she was there until her security decked me while escorting Avril to the restroom. Very rude!
Source: Hollyscoop