I think it is one of those phrases that means different things depending on the context/person. I always think oral sex when I say it, but I know other people would probably say it is the act of sitting all over the face and not necessarily oral. Some people might like the crushing powerlessness of it.

I am assuming a giant sculpture of a cow that is made out of butter. Probably for a county fair.

Umm…can I have some candy?

Well. I have achieved this feat as well. Now I am a straight man, and I agree that it is more like sucking a dick than getting your dick sucked. Taste didn’t bother me, so whatever about the cum. I’m sure some people will claim I’m not straight because of this. I would point out if that makes me gay than when you jack your hard throbbing cock to cum then wouldn’t that make you gay? Sexuality is a spectrum, get over it. My back did end up sore, so I only did it a few times.

Here’s an old political cartoon trying to explain it, but if you would rather read.

https://www.ushistory.org/us/43b.asp