Guess I could elaborate a bit on this, since I have a lot of free time now. ha.
1-If a girl comments on it, I usually smirk a bit. An ex of mine said she noticed it long before we started dating and told me that a lot of people comment on it to her. It's rare that a woman would just comment on it, so I don't really think much of it, then she pointed out that I keep my cock pointed to the right, and my keys hang from my belt loop right over it, so when my keys jingle people look at it. I never even realized I did that, but she said that's how she noticed it.
A few times at bars, a woman has pointed it out after some chatting and drinks. Again, the smirk usually comes out and a thank you.
2-Gay guys notice it a lot, and point it out a lot. haha. So, I say thank you, glad it meats (pun intended) their standard. I was at a party at a friend's house once, him and his two hubbies would throw these great parties. Needless to say, plenty of people from all sexual orientations were there, and one guy dropped to his knees in front of me and said "that is a gift, it needs to be worshiped" and he asked if he could touch it. I said "thank you, but its a touch with your eyes kind of thing." he was kinda sad, but it was funny.
3-I don't think a straight guy has ever pointed out my bulge actually. That's okay though. I have caught a few straight guys when they've noticed it though. I used to work in sales, and wearing slacks certainly accented it quite a bit. I can recall a few times a husband and a wife would both notice it, and seeing the husband's shoulders kind of slope down when he noticed his wife checking it out was an empowering feeling, I knew she was certainly going to buy something then. haha.