We were having sleep over and looking at Playboy. We could see we all had boners. We were so horny, we played truth or dare but we all did the dare because we all wanted a reason just to get naked or see or touch each other. We stated just showing each other then jerking each other. The first dare was to pull underwear down to knees for like 10 seconds. Then drop them to ankles. Then we ended up taking them off. Just went naked together.

I used the old show me yours, and I will show you mine.

Growing up always started out peeing together which lead to comparing. moving forward into teen years it was porn which lead to how big is your boner which lead to once again comparison on dicks. I did this with a few guys growing up but only jerked with one. We started out comparing pubic hair which lead to hardons and one thing lead to another we were jerking off, nothing planned just happened. From then on when we felt like it we would jerk off was a great time in life. Now a days you need planning to make it work Craigslist was great for that because you both are after the same thing

I have used two effective "lines".
"Are you circumcised?" Regardless of the answer (both times were yes) I follow with "Can I see it?" Both times I ended up seeing it and sucking it.

Twice I've said "We should get naked." Both times that was effective and we ended up sucking each other's cocks.

Now, you can't just say this to anyone but when you think a connection might be possible they're both good opening lines to achieve your goal of getting his cock out of his pants.