Yes. Most of the C&Ds I've received have been mundane. My favorite one was over a set of game rules that I wrote that were very vaguely similar to a board game that was on the market.

That one was so ridiculous that I didn't consult my attorney at all about it. I just told the company to sue me. I never heard from them again.

Mine was where a customer who had signed a contract with ${company} to make and distribute an app, sent a C&D to stop distributing the app.

Not even sure how that happened. New lawyer? Lost paperwork?

Yeah, we received one about having t-shirts that said "network ninja" for instance. We held a small party that afternoon celebrating that someone actually noticed our marketing.