>Uh, Gibb - that wasn't a very helpful comment ... would you care to elaborate?

"Simp" is a derogatory term you call someone (typically a male) who you think inappropriately, obsessively, PATHETICALLY ...supports, sucks up to, fawns over, white-knights ... someone (typically a female).

What that someone is doing can also be called "to simp" (noun changed to verb). The object of the simp's attention is often assumed to be looking for attention -- e.g. a female posting a photo of her butt or being overly cutesy -- and the simp is considered especially pathetic for falling into the trap of giving it. Can be used ironically (e.g. call yourself a simp) and metaphorically (e.g. die hard Trump supporters as simps for Trump).

I'd guess it's related to sympathetic, not simpleton.

That sounds so silly to define in a formal way, and now you know why I didn't feel like doing it.