Do YOU ever "sabotage" your friends?

Yes..and no. Yes I suppose I do with ONE friend, but I believe I have a good reason. She's, in a nutshell, very obsessive about her weight. She's not ill but if it wasn't for my "support"/"sabotage" she'd be under 100 pounds and probably end up quite ill.

PS I don't generally do it to others at all because I HATE it when my friend does it to me.

I was about to type something very similar. I have a friend who doesn't look after herself properly and our group of close friends believe she may be undereating and exercising excessively to lose weight that she REALLY doesn't need to lose, so we invite her over and cook plenty of food and have cakes etc.
Sabotage... yes, you could call it that, but it's because we care and want her to stay healthy.
We all cook from scratch on these occasions, so we're not offering junk food, it's all reasonably healthy, well balanced meals (apart from the cakes!!) it's just that there are far more calories on offer than she would eat if left to feed herself!