It's a kneecap
People often make references to people being on their knees. When the reference is made, it is implied that they are down here performing indecent acts. A lot of other knee references surround the word irony, including spelling it iron-knee.
Some knee puns are used when cracking on someone if they have knobby knees, alligator skin knees or just plain ugly knees.
Here we’ve added the most popular and viral knee puns from all over the Internet. We have taken the best ones we could find, including the ones you guys have sent to us, and added them here. We are always adding new content to this section so be sure to check back often. While you’re browsing our collection of jokes, be sure to rate your favorites and share with your friends and kappit!