The couple were ''super cuddly and affectionate'' as they drank Dom Perignon champagne and Grey Goose vodka in the gambling city on Tuesday (21.08.12) to celebrate their forthcoming marriage after the Nickelback frontman popped the question to his girlfriend of six months on August 8.
An eyewitness told Life & Style magazine: ''They went to 1 Oak Nightclub in Las Vegas on August 21 to celebrate their engagement.
''Avril arrived first with a bunch of male friends and bodyguards, then Chad showed up later and met them inside. Avril was so excited to see her man.
''They were super cuddly and affectionate. They drank Dom PÃ©rignon and Grey Goose.''
A wedding date is yet to be set for the pair's nuptials, but vodka looks sure to be on the menu as Chad revealed the 27-year-old singer is a big fan of drinking the spirit.
He recently said: ''She can pound the vodka.''
The 37-year-old rocker previously revealed the pair had some ''amazing'' chemistry when they were working on new music in the studio and he admitted the 'What the Hell' hitmaker has ''a lot of tricks in her arsenal''.
He explained: ''We just started flying on all these songs ... 'Let's do another one, let's do another one.' It was amazing.''