Lisa: Why isn’t Dad ever interested in anything I do?
Marge: Well, uh, do you ever take an interest in anything he does?
Lisa: No. Well, we used to have burping contests, but I outgrew it.
Marge: Hmmm. Well, if you want to get closer to him then maybe you should bridge the gap. I do it all the time. I pretend I’m interested in looking at power tools, going to those silly car chase movies, and . . . some things I’ll tell you about when you’re older.

When I was young I thought the joke was just about sex, but in the show Marge clearly likes having sex and wouldn't compare it to looking at power tools.

Is she talking about blowjobs? Or anal?