Katy Perry Is This Week's Most Valuable Partyer!

Singer pulls double duty in London and gives back to two important charities in the process...but which Katie is getting slapped with this week's party foul?

Katy Perry is awesome.

The pop powerhouse is currently hard at work on her California Dreams tour, and last night across the pond in London, Katy was out late for a good cause.

First, she performed at the Hammersmith Apollo to rave reviews while donating some of her proceeds to Red Cross relief in Japan.

Most singers might call it a night after that, but not Katy. She then headed to the Radio 1 studios at 1 a.m. to be on the air for yet another charitable cause...

The "Firework" babe was a guest on Chris Moyle's record-breaking 51 hour BBC show, which raised $2.4 million for Comic Relief. Being the good sport she is, she even donned their signature red nose for photogs when she exited the studios.

It was definitely a late night for Katy, but good deeds are worth staying out past your bedtime and miss some beauty rest.

Speaking of sleep-deprived, this week's Party Foul goes to Katie Holmes and no, it's not for letting Suri pick up penis gummies.

Katie's getting called out for bringing 4-year-old Suri to Serendipity so late. The mommy-daughter duo was out after midnight enjoying desserts in NYC on Tuesday night.

We're all for ice cream dates, but can't Katie take her young kiddo out at a more reasonable hour? Or find an adult friend to join her on her night-owl outings instead of her poor kid?

Let's leave the late nights on the town for Suri until she hits the teenage years at least, OK?