How do I explain that?

So the other day we were at a McDonald's playplace with my parents and the kids were playing. Seth was running around and making this horrid, loud, screeching, siren noise. I went over to him and told him to stop making that loud siren noise. He said, "Mom! It's not a siren!" So I said I don't care what it is, just stop because it was an irritating noise for everyone in the playplace. Seth responded loudly by saying in front of EVERYONE else in the playplace, "Mom! I can't stop! It's my mating call!" I don't even want to know what the grandfather with his 4 year old grandaughter thought of this announcement. In an additional note, one day earlier we were at a restaurant and Isaac was "talking" loudly and making lots of noise. Seth asked then if that was Isaac's mating call. I should have known at that point that it was on Seth's mind and would turn into an embarrassing moment sooner or later. As a backstory for this incident, my brother started working with Seth several months ago to make obnoxious noises and call it his mating call. He even trained Seth to hoot specifically at women when they walked into a room. In the past, it never manifasted itself beyond Dan and Seth hooting at Aunt Lauren. But now it's getting embarrassing. Thank you Uncle Dan! I will add this to the long list of awful and inappropriate things one of my brothers has taught my children.