I was struggling to find a Mother's Day card a couple years ago. There are the treacly sentimental ones which I hate, and the allegedly funny ones. I always thought a good all-purpose one would have a large bolt/screw on the front and open up to "Thanks for screwing me up so comprehensively mom." Wait, that's ™ lol.
So I got one that seemed fine, said something like "for the nicest mother" etc. I mean the truth is irrelevant when you're getting a card like that. But when I was going to sign it something about it made me pause...I kept looking at, feeling like there was something just below the surface I was missing...
Then it hit me: just transpose the first 2 letters in "nicest" and you have "incest". Needless to say I didn't point that out to mom.