Robert downey jr photobomb

Kim Kardashian, Paris
Hilton and P-Diddy
Photobomb Kanye West
and Zac Efron for the
"UltimatePhotoBomb"
Title—Here's Why

When Paris Hilton and Kim Kardashian reunited in Ibiza, little did they know they would be part of the "#UltimatePhotoBomb," as noted by the hotel heiress.

Many celebs celebrated Givenchy designer Riccardo Tisci's 40th birthday on Aug. 1. However, little details of the bash were reported, so we had to turn to the guests' Instagram pages to fill us in with what went down.

While Kendall Jenner smooching Justin Bieber was one of our favorite photos, we believe Paris Hilton and Kim Kardashian pictured together (after several years) was the best!

Yes, they each shared the same black-and-white photo, but we're talking about the photo (below) of them unknowingly photobombing Kanye West and Zac Efron's picture! And yes, P-Diddy photobombed their picture as well.

Check out 11 other photobombs from stars and you'll realize that this is the ultimate pic we've seen so far!