This actually just happened recently! We were on a vacation in the south of France, with both my siblings, their spouses, and a few others...
I walked in on my older sister's husband changing for the Beach, and I got like a full on view...
So when we're out drinking later (idk why) but I made a comment to my sister, and my younger sister-in-law, something like "idk if your husband is a grower or a shower, but he certainly has mine beat either way".
They were both like "wait what I don't understand " so I said "I was just complimenting the size of your husband, I don't know if it like gets a lot bigger,.or ... Idk whatever he is very well endowed"
My sister said "a. Gross, b. What do you mean? Of course it gets bigger, that's how they work?!"
I said "look, I saw your husband's penis unerect, and it was longer and thicker than my husband's when he is hard"
At which point they both said something like "OH No.... that's unfortunate,.and also I didn't need to know that"
I said "eh it's.fine,.we.have figured out alternatives..."
I only say all of this because later that night my younger.brother started teasing me saying stuff like "where is your micro-man husband" and "I guess he is the baby of the family" while wagging his pinky...
So now there.is that