Katy Perry just weighed in on music’s biggest bitch sesh — calling Taylor Swift a full-on hypocrite for accusing Nicki Minaj of taking down a woman.

Perry thinks it’s hysterical Swift told Nicki … “It’s so unlike you to pit women against each other.” The joke, to Katy … is that Taylor went for her neck with “Bad Blood” — and proceeded to make a ton of cash off the song that’s all about throwing shade at Katy.
Nicki took notice — and favorited Katy’s tweet.

Taylor might wanna call for backup.
TMZ