Tbh my only gripe with this post is the assumption that because a man is explaining something to a group of women, it's automatically mansplaining. Although I guess it's a joke so whatever.

Going meta is always allowed. Just say you're dumbing it down, that you don't mean to be condescending, and invite them to interrupt if they already understand.

I usually have the opposite happen to me. When someone happens to ask me about something, I tend to go into the specifics and give detailed information that I consider relevant and/or useful, but get complained that I'm "showing off" or being a jerk trying to make them look dumb. I kind of get what they mean, but I still can't figure out where the line is when considering the other person knowledge of something without coming off as condescending or rude.