I have tried shazam, sound hound and the lyrics I'm at a loss its a nightcore song I'm pretty sure (NSFW because I'm not sure how this sub is with firearms) :
Nightcore - Swing It - YouTube
Nightcore Little Swing : Free Download, Borrow, and Streaming : Internet Archive
Steam Workshop::Adoms Gmod
Stream Nellie | Listen to Pac-Man playlist online for free on SoundCloud