I can’t say it’s common, and wouldn’t ever have considered asking some random good looking guy to join us, but straight guy MFM is probably more common than you think. When men on the internet talk about threesomes they seem to be thinking about 2 women, but I’ve only done the other kind and it seems like way more fun - I’m straight so nothing really exciting about adding another woman, but two guys? So many things you can do whether they are into each other or not.

I do think it’s more common for couples to approach women though, as I have been propositioned by couples and probably all women have.

MFM is two straight guys, one lady. That is fun. I am straight so yes, that means I have done straight threesomes. Have also done some with bi guys, but it’s not a lot different from the perspective of the lady, maybe slightly more relaxed.

FMF I don’t understand - I agree that is probably no fun unless the ladies are bi. But it’s entirely possible to have a good time with two straight guys.