Perhaps it is not the explaining but rather the timing. Say you have 3 kids, 5, 10 and 15 years old. You going to sit them all in a room and have a sex education / awareness talk with them or are you going to do that at a time that is more appropriate? I don't think having that chat with a 5 year old is appropriate.
Problem is. Your not thinking
Know many 5 year olds playing? And there is a very very strong chance that your 10 year old probably already knows what it is from his friends.
More likely they will and have heard the term on TV then read it on screen along with an entire host of other words or names. Most of them far worse.
Any event. Remember. Very little vox was used back then
There is no appropriate/inappropriate time to have a talk to your kids on any subject. When the subject comes up the subject comes up. "Its a movie for adults only where they do adult things and use lots of bad words. You wouldnt like it" was the simple answer I gave mine. And it was a hell of alot easier to have that conversation then it was to tell my kid (at 5) when I had cancer and was going to loose my hair and turn a funny color. But while I was going to get real sick at times. I probably wasnt going to die.
You're the parent. Its your responsibility to explain things to your kids whenever they might come up. No matter the subject And like it or not, life is unpredictable and uncontrollable. You dont get to choose which obligations you have to confront now and which ones you can defer to a later time because you deem them inconvenient at that moment.
And thats what it is really. Inconvenient. Not that its hard to explain to the kid. Kids are tough. Much tougher then their adult counterparts in many respects. If you put things in simplistic but honest terms. They understand pretty much anything.
Most parents never have "the talk" with their kids till well after their kids have figured it out for themselves. That is. IF they have it at all. Usually because its inconvenient (this is what we adults really mean when we say the timing of something is inappropriate) because there never is a convenient time.
And if and when the parent does get around to it. Like I said. the kid already has it figured out for themselves and would quite frankly usually rather be doing anything else including mowing the lawn, cleaning the attic on a hot summer day, or going to the dentist then listen to their parent ramble one about something they already know.
Out of respect they politely pretend to listen in the same way a "Peanuts charactor hears adults. Like so

But their mind is any of a thousand other places and quite frankly by the time you deem the conversation appropriate. You might as well be talking to a brick wall.
The "appropriate" time. Is when they ask. No matter what age that might be