We had a command meeting about statements like this, and they were ruled not that bad. But if the person had an issue with it, it's best talk with both parties so both have an understanding. Jumping straight to a warn will only cause problems.
Not everyone enjoys it, but if no one can make simple jokes, it'll be a very stale experience and everyone will have to worry about every little thing they do. It's not a good environment like that. Please talk to each other first. If that doesn't solve the issue, then continue with sits, and let staff handle it. If you don't feel capable of confronting that person, let staff know before hand, and let them know you just want them to get a verbal.
also panda, saying it once is good enough. no need to repeat it over and over again. That's how you upset people.
Not leaving any support on this one.