We know Kylie Jenner can't help herself when it comes to shading her frenemy Blac Chyna. But her latest dig at the pregnant reality star might have gone too far.
The teenage millionaire threw a birthday party for her King Cairo, the son her boyfriend Tyga shares with Chyna, and the soiree was a "slap in the face" for Chyna — not because Kylie's playing stepmom to her son, but because the youngest KarJenner literally stole her party theme right out from under her.

On Saturday, Chyna threw her four-year-old son a festive, Ferrari-themed birthday bash with a three-tiered cake and lots of presents:

Cute, right? 
Well, cut to 24 hours later, and Kylie and Tyga threw their own party for the toddler. The theme? Ferrari. But they not only stole Chyna's idea — which, according to TMZ, she believes was leaked to them by a member of her reality show production team — they outdid her by throwing the most epic luxury car bash we've ever seen:

According to sources, Chyna is happy that her son had a great birthday, but hurt by the double-cross from her own staff and — of course — the fact that her ex and her future sister-in-law would feel the need to resort to such pettiness.
Side note: it's interesting that Tyga had the cash to throw such a lavish bash after having his own Ferrari repossessed in broad daylight just a couple of months ago. Watch BET Breaks above to see how it all went down.