Q: What did the mother lion say to her cubs before dinner?
A: Shall we prey!

Explanation:  Many people pray before dinner; they say words of thanks to their god, spirit or higher being.  Prey (with an ‘e’ not an ‘a’) is the animal that is being hunted by another animal.

This joke plays on the words pray/ prey with the lions “preying” before eating not praying.  Here is a lion that appears to be praying.  By the way, prey in regular usage is not used as a verb by itself but as a phrasal verb “prey on” or as a noun.  But that is why I like jokes: anything is possible!