*sigh* teenagers

[tracilicious]

I'd just turn a radio on downstairs too. Or maybe a casual, "Hey could you two keep it down up there," if it's really bugging you. I think it's a sign that he feels really comfortable in his own home (not too common for teenagers) to be doing it while you're there. I wouldn't want to make him so uncomfortable that he feels he needs to hide his sexuality. It's totally normal.