A plausibly deniable nickname for an individual or a very good friend for which you want to pretend that you have no sexual attraction to. Commonly used as a greeting or petname.
"Hey there lustmuffin." (translation: Wow you're really hot, but I'm too chickenshit to outright say so. I hope you know what I mean.)
I mom just pulled some blueberry muffins out of the oven, they looked good to eat, but even better as a lovemuffin. So I took it to the bathroom, treated it, then enjoyed it as a nice afternoon snack. Al Naturale