Now that she’s ditched RUSSELL BRAND, KATY PERRY’s prowlin’ for brand-new love, so she took a chance on romance by passing her phone number out to passels of cute studs she spotted at chi-chi Oscar parties, including ELTON JOHN’s annual bash – but Ms. Siren’s scheme backfired big-time!

“Katy got calls from some real creeps, and realized that guys she gave her number to were passing it on to other guys,” reports a friend.

“She told me, ‘I might as well have written it on a bathroom wall!’ ”

Katy even got calls from drunks – like the guy who told her: “You don’t know me, but a friend of mine said it was okay to call!”

No, it’s NOT, Katy howled – and hung up!

Said her pal: “Katy’s a superstar, but still has this punk rock attitude – wanting to be devilish and carefree.

"But friends are warning she’d better get much more guarded, or she’s going to find herself in trouble – maybe even with a stalker.”

(For a good time, call…?)