Katy Perry went to Las Vegas last night -- where she was partying with her 90-year-old grandmother!
Katy, husband Russell Brand and Perry's nana, Ann Hudson, were all photographed together at Strip Steakhouse at Planet Hollywood last night, where they celebrated Ann's 90th birthday.
With 15 friends and family members in tow, the group also checked out Cirque du Soleil's Viva Elvis show at the Aria Resort & Casino, before Katy and Russell split to play some blackjack on their own.
Somewhere along the way yesterday Katy tweeted "Happy 90th birthday Grandma Hudson. You're the reason why!"
Check out the party pics!
