I'm bisexual, he's straight. But now I'm confused

Short and simple. I'm bisexual, and my best mate is straight.

We had a conversation one night that utterly confused me about if he is straight. I told him last year I had feelings for him and told me he was straight.

We got on the topic about sex and girls and what normal straight guys and probably bi guys talk about a lot. But the conversation somehow turned to talking about our dicks and the sizes, which for me was really weird for me to hear him talk about his own dick to a bi guy and one that is attracted to him. I could be thinking too much into it, but it has gotten me confused and whether or not he could also be bisexual. Our friendship was almost ruined coz of the fact that I'm bisexual and that I was also attracted to guys (and probably coz I was attracted to him).

But what really got me confused was the fact that the concept of sexual intercourse between a male and female my friend finds that really weird, and the look on his face trying to imagine it confirmed that he found the idea weird. I probably am thinking too much into it, and I probably won't do anything about it coz I don't want to ruin things between him and I.

The question I was really trying to ask is: Is it normal for a straight guy to talk about his dick and the size to a bisexual person, or more so openly to the very person who finds him attractive?