Sometimes with incest, people just can’t say what they want, they need plausible deniability. Or implausible deniability, in certain cases. You know what, I think I’ll make that a tag.
Five minutes later: “What about this underwear? Can you fuck me by just pushing the crotch piece aside, or would the fabric be uncomfortable against your cock? This information is really good to know! You can’t trust a guy you’re dating to be honest.