Oops! Kim Kardashian Forgets Sister Kourtney's Birthday

Yesterday, Kourtney Kardashian's friends and family celebrated her 42nd birthday with everything from flower bouquets to social media tributes, however, it seems her younger sister Kim forgot just how old she was turning. On Instagram, the birthday girl showed followers the opener of Kim's card which read, "Happy 41st birthday!" Yikes!

Luckily, Kourtney brushed off her sister's forgetfulness with a laugh, saying, "So Kim thinks I'm 41, so I guess last year really didn't count."

The Skims creator responded with a sheepish, "My bad." However, she still honored her big sis by posting an array of throwback photos, including some from their early years, and some thoughtful words to cap off the big day.

"Happy Birthday to my Armenian Queen," Kim wrote in the caption. "The person on this planet I’ve known the longest! The person that will try any beauty treatment with me LOL about Kourt...There’s NO ONE like you! You always know what you want in this life and will never conform to what others' ideals are and I admire that so much! You always stick up for what’s right and have become the best therapist a girl could ask for! I love you to the end of time and beyond! Have the best birthday, you deserve it all!!!

Kourtney's boyfriend Travis Barker also celebrated the day with a social media post, although it's definitely more NSFW. Between cute couple shots of the two, he also included a photo of his girlfriend's bare backside, as well as a video of her sucking his thumb. "I FUCKING LOVE YOU," Barker said in the caption. "YOU’RE A BLESSING TO THIS WORLD."