Don't keep Kim Kardashian waiting!

Kourtney and Khloé learned this lesson the hard way after the KUWTK stars pushed her sister's workout back half an hour.

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"Okay, seriously, Kourtney and Khloé, f–k you. This is so rude," the mother-of-two said on Snapchat. "I've been sitting in my garage, waiting for the trainer, for 30 minutes. I do have a life."

In a separate snap, Kim, who is wearing Yeezy Boosts, says, "So me and my friend Nicky are waiting for Joe to get here because my sisters' workout started 30 minutes late. Thanks a–holes."

Despite the adorable bunny filter, Kim, 36, was all business when she sent the warning snap.

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When her trainer did eventually show up he put all the blame on oldest sister Kourtney.

"So, tell me Joe, who was late?" Kim asked her trainer as he walked in holding gym equipment, before he responded, "At first, Kourtney was."

Khloé also called out Kourt for being late on her personal Snapchat, saying, "The queen of being late for workouts. Our workout started 30 minutes ago. I've been waiting for you!"

However, it wasn't long before Kim was working up a sweat.

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Kim also used her social media platform to support husband Kanye West and his fans who want the "Famous" rapper to headline next year's Super Bowl halftime show.

"Never too early. #KanyeForSuperbowl52," one of the tweets read.

For a look at the KUWTK stars then and now, click through the gallery below!