When you either do something small as kiss to actually have sex with a sex that you normally wouldn't and you never had or wouldn't date. Experimenting does NOT make you bisexual or anything like that.
1. Did you hear that Sarah French kissed Jill? I never knew she was bisexual!
2. She's not shes just experimenting, she told me herself.
The act of someone / people trying out new things. More specifically experimenting with sexuality. What most people don't realize is that we all have bi-curiosity, some just show it more than others. See Kinsey Scale