Trendy Lesbian is a female who, upon joining college/high school/equivalent, becomes friends with other loser feminists who have no time for "ordinary" and/or "normal" people.
The Trendy Lesbian will discuss, with her Trendy Lesbian friends, how uncool it is to be straight, and how edgy it is to be "sexually attracted" to other females, and that is what makes them superior and individual.
When conversing with a straight female, the Trendy Lesbian will openly mock the practice that is a heterosexual relationship, and ask her friends such things as "Would you sleep with a man? I wouldn't sleep with a guy. I just think that it's weird and un-edgy." while the straight female wonders why she even allowed herself to respond to the Trendy Lesbian in the first place.
The Trendy Lesbian has more often than not, never slept with another female, and will stretch to kissing one at a party to keep her reputation as a "lesbian" untouched. The Trendy Lesbian has more often than not, never slept with a male and uses her "homosexuality" as an excuse for being ugly/unloved/oppressed by her parents/ignored at school etc.
Trendy Lesbians travel in packs, and will have an extended Trendy Lesbian network consisting of a large number of other Trendy Lesbians. They will meet up occasionally to moan about how there are no other Lesbians in their area, despite there being a large group of them sat together, who could in theory, just sleep with each other if they were really all that bothered.
Girl 1: College is a new place full of exciting people. I need to be popular. I'm suddenly a lesbian because it's cool and original, and nobody else will understand me.
Girl 2: I'm in your shadow. I'm a lesbian too, because you said it's cool. Does that mean we should sleep together now?
Girl 1: Definitely not. We'll drunkenly kiss at that party tonight in front of everyone, and then maybe pretend we touched each other's breasts a little bit.
Girl 3: You're lesbians? I'm one too now.
Girl 1: That's so edgy of you. Let's go mock straight people for being conformists.
Straight Person 1: Look at those Trendy Lesbians over there.
Straight Person 2: I want to punch them for being shit.