This poem I find funny and even cute in a way. The delivery of this poem is very surprised. You can tell the kid doesn't really know about the world and he's so innocent.
It's quite obvious that his mom is a lesbian woman but in the kids mind, he doesn't understand why the other woman has her clothes off. He thinks she'll get cold but she replies she's devilishly hot. And it just goes over his head.
Why must sexuality always be in the gutter? I think it prudent to remind ourselves that regardless of fairy tales with princes and princesses, we all owe our very lives to the notion that sexuality is real and wonderful. We can play charades all our lives long, if you desire the appearance of this sort of self-defined-ostrich-head-in-the-sand-prudence, surviving only for the sole reason to support monogamy because for some reason society places higher priorities on such than actual reality, which is where men and women are sexually attracted to one another. It's not in the gutter - but quite wonderful and intimate. We can be true to ourselves while still being monogamous - without the charades.