Running into your ex when you least expect it can often be an awkward experience, even for celebrities. Katy Perry recently had an unexpected run-in with her ex John Mayer at a concert, and the "Woman's World" singer had the most hilariously relatable reaction to the situation.

Perry attended Sabrina Carpenter's Short n' Sweet tour stop in Los Angeles on Monday (November 18) and as she sat in her seat, Mayer arrived to take his own seat close behind her, per People. When she noticed her ex walk in, and realized just how close he was, she grabbed the railing in front of her and leaned over in disbelief. However, despite her initial reaction, she quickly turned around to shake his hand and chat for a bit.

Perry's reaction was captured on video by a fan in the crowd and shared to social media.

Perry and Mayer dated off and on from 2012 to 2015. The "Firework" hitmaker has since moved on with fiancé Orlando Bloom, with whom she shares 4-year-old daughter Daisy Dove.

In September, Perry threw shade at some of her exes by revealing that she is "no longer attracted to narcissists," with the Daily Mail noting it as an apparent dig at ex-husband Russell Brand, who she was married to for 14 months before he broke off their marriage over a text.

Pencil it in: