Anonymous parent who made this ridiculous complaint: it’s a fucking dictionary, not a how–to manual. You does not need to be a linguist to realize that the definition of an act is not the same thing as instructions about how to do an act. For example, telling someone what driving is (operating an automobile) is not the same thing as telling them how to drive (too long to put here).
On the other hand, perhaps the school should ban other “obscene” books. One such book would be the Bible, from whose Song of Solomon God is left out, while still finding room to have the whole book be a love poem that contains explicit eroticism. After all, if someone is absolutely unable to talk to their kid(s) about something sexual in a dictionary, they can’t possibly be able to do the same thing to their kid(s) when something sexual comes up in the Bible, right?