honestly, i'm surprised too! a lot of the time it doesn't feel very punnable, and yet,

sometimes inspiration strikes, but normally it takes some effort. i pick a theme, like the time of year, and go through related words looking for good candidates
making it fit is a challenge because the pun has to stay close enough to both the pronunciation and spelling of the original word (vowels are especially tricky) and also be smooth to say, which is tough when my name is bookended by a stop and a sibilant!