One of my characters I hope to play some day is a half orc hexblade warlock who doesn't realize he has magic powers or that he made a pact. His "casting" involves yelling intimidatingly and waving his arms, sometimes throwing certain things.

If anyone asks where he got his favorite axe (which is always conveniently "on his back" when he needs it, despite him constantly forgetting it), he'll explain that he traded part of his shoe for it.

Any party members that try to explain his pact are met with disbelief or confused facial expressions before he inevitably moves on.