Would you be mad if your brother kept this info from you?

My nephew is 10, he's adorable with his little curl hair and green eyes. My sons also 10, they are inseparable. So my sons door was cracked today after their pop warner practice. I don't know why (im very immature lol) but I peeked in the room. the two boys were watching a music video I think Kanye west. My nephew was going nuts over a girl in the video. He was swearing saying "Oh my god I want to eff her so bad." (but actually saying the real word.) He then said "I'd do her like this" and started violently a pillow as my son just laughed his head off. Then he started going in to details saying "I would leave that *ussy in stitches, she wouldn't be walking right for a week" Apparently my son understood him because he's just laughing at every word. I finally had enough and barged in. Only place I can imagine him getting all this knowledge from is basketball. They train with kids up to 17. They also play on a 12u team. They are both really smart and mature also. My son didn't say anything so i'm not going to punish him. My nephew is begging me not to tell his dad because they have a football game tommorow. i told him I'll think about telling his dad afterwards so he could play. Should I? would you be mad if your brother kept this info from you?