I have been making my own up! If you read them, it's sadly obvious.
But as I see that some are repeated I fear you may be right.
I love puns, and wordplay and always have done, so I was really happy when I saw the competition. In fact grannyknot pm'd me in the past because she said her OH is just the same.
OH and I make up puns in the same way that others do crossword puzzles. Which was why he said at one point that if I continued to gaze at the screen looking for inspiration I would wake up looking rough puff in the morning, with a pasty face.
I hadn't realised I was lame.
DBH says I am a wordsmith, I think I prefer that. Still, you can't win them all. 
I did wish I had done some homework first, though. Never having been a purchaser of mason cash items (although I did inherit some very old specimens from my grandmother) I hadn't realised that they had a range of items with puns on the sides. As a result I started to tailor the length of my crumble humble contributions.