I had a similar thing happen as a very young child, though my combination was not fuck but rather dog. I thought it was so funny that the combination for these two animals was a third animal that I began to announce "what would a frog and a duck be?" But before I got to my punchline my art teacher rudely interrupted me and told me I couldn't say that.

It took me many many years to understand what was so taboo about the word dog :(