Can a straight guy have bisex?

This may sound like a strange question, but I wonder if a guy can be straight, but also participate in bisexual forms of play. Or, does having sexual contact with another man necessarily make you bi?

What I'm getting at is this; I've had a handful of sexual encounters with other guys over the last 20 years, but beyond basic friendship, I have never had any real emotional attachments to my sexual partners. That that is to say I've never had romantic feelings for another man. In each case, it was only a matter of two buddies helping one another accomplish something they would do by themselves anyway. My activities have been fairly tame; primarily mutual masturbation, frotting and oral sex when the mood is exactly right. Does that make me bi, or just a straight guy with normal curiosity bi ways?