A tape worm ... seriously?!

I'm pleased to say my office provides spring water. Unfortunately, the water cooler is located in a co-worker's office instead of in a common area. I went down to the cooler this morning and found the water empty, yet again. I grumbled, and my co-worker noticed. So, amazingly, he came over and helped me get a new bottle on the cooler. After he sat back down at his desk but before I left his office, he says to me completely seriously, "do you have a tape worm or something because you're just disappearing?" I don't know what my face looked like, but I'm sure it wasn't pretty. Whhaaaaa?!! Yeah, I'm such a stupid person that I would knowingly ingest a tapeworm so as to lose weight! Perhaps he was trying to give me a compliment, but knowing him, my guess is that instead he truly thought I'd do something like that! I did my best to compose myself and answered, "no, remember I had gastric bypass surgery last June?" His response? No, not the normal congratulations or you look fantastic but I get, "oh" and that's it. I've had even completely oblivious professors say things to me over the course of the last 8 months, but my co-worker who knows I had WLS asks me if I have a tape worm. Nice.