So, Rob Kardashian is back on Instagram -- sort of.

Six new photos popped up on his account on Monday (January 5). Why is this a super-major, important, LIFE-OR-DEATH BIG DEAL? Well, because Rob deleted every Instagram he ever posted back in May after skipping out on sister Kim Kardashian and Kanye West's wedding.

Speaking of Kim, it looks like she's responsible for yesterday's selfie spree. She and Khloé apparently grabbed Rob's phone while he wasn't looking, and revived his Instagram account without his knowledge.

"I'm with Robbie and I took his phone!" Kim captioned one of the pictures. "Since Rob doesn't post selfies I think I should! He might delete them soon since he's a tweeter and deleter."

"Koko take over," Khloé captioned another.

Brilliant hacking, ladies -- except for the whole trail of photographic evidence thing.

Anyone wanna take bets on how long it will be before Rob realizes what his sisters have done?