Star Trek: 10 Things You Didn't Know About Captain Pike
8. His Days In Security
After working as a test pilot straight out of the Academy, Pike had a brief career as a security officer. Near the beginning of the Strange New Worlds episode Children Of The Comet, Captain Pike told his senior staff a story of one of his most embarrassing moments as a security officer.
Apparently, Pike (an ensign at the time) got into an altercation with a Nausicaan. Somehow, during the fight, the Nausicaan ended up pantsless, and the young Ensign Pike ran after him, phaser in hand, only to trip and get caught on the Nausicaan's discarded pants, allowing him to get away.
After the mishap, Pike's lieutenant pulled him aside and told him that security may not be the best fit for him. In the scene, he never mentioned whether or not he took his lieutenant's advice. It's possible that Pike learned from this experience and remained in security for years before serving as Robert April's First Officer aboard the Enterprise.