Just supervise a little

My DH just can't help being facetious with the kids. I beg him to stop teasing them so much, but to no avail. My main problem with it is not that it seems mean, but that the kids are smart enough to learn this tongue-in-cheek technique and then use it on me.
I can't really be sure whether my eldest son's teacher told him he should bring his pet rats to school or that he absolutely should not.
If my daughter comes home from school and tells me all she ate for lunch was cake and mashed potatoes, and I start a lecture railing on about the nutritional value of foods and the importance of balanced meals and protein, will I be teaching or just playing into her hands?
However, it is (according to his wacky psychiatrist) a good way for Orangeboy to learn about humor, sarcasm, teasing, etc. So now DH has full license to confuse and fool Orangeboy to no end! The boy is catching on these days, but he can be a little gullible. This makes it difficult to decide whether Orangeboy is taking a facetious remark from his Dad seriously or if he is playing along and replying with a little wit himself.
For instance, this weekend we went by Home Depot and bought some outdoor furniture. As we were all walking outside where the furniture was to be loaded. DH says, to our trio of young gradeschoolers, "OK boys, you get ready to load the furniture and your sister can back the truck up!"
Now, not only are our young sons skinny and not at all into heavy-lifting, little sister is only 8 years old and she is visually impaired. So we have now strayed a bit into the area of dark humor - or at least light gray.
But Orangeboy replies, with all seriousness in his lispy, chin-down voice, "OK, but I think you should at least supervise her while she backs up."

LOL! That is just classic.