Dont be sure he is so straight.I bet he wants to get a bj from you so he teasing you sending his dick pics.I would advice you meeting him alone and ask him to show his cock in person.If he does then give it go and suck his cock

No, it ain't normal. When a man sends photos of his cock to someone he's trying to interest that person in his dick. He wants to fuck you or have you suck him off. It's as simple as that. That's not to say that he isn't straight, though it's possible he's not. More likely is that he is indeed straight but is open to do a bit of switch hitting. Most straight men are.

More important questions are: Do you like what you see? Do you want his cock? If so, go for it. Volunteer to be his fuck buddy and/or his cocksucker. The next question almost always is: Will it spoil our friendship? My own experience is that it will not. I've had several straight friends over the years and with most of them we eventually ended up having sex. In no case did it spoil our friendship. Indeed, it brought us closer together.
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After I wrote that I went to your page and saw that you identify as straight. Hey, that ain't no big thing. A lot of straight guys fool around with their buddies.