Sarah Michelle Gellar On Grosse Pointe (2001)
Grosse Pointe was a short-lived series on The WB about a cast of actors who star in a Beverly Hills, 90210-like primetime teen soap. It featured a few cameos from other WB stars, though no one as high-profile or memorable as Buffy herself, Sarah Michelle Gellar. Marcy (Lindsay Sloane) befriends Gellar as the two share the same yoga class, and then Gellar ends up being cast to guest star on Marcy's show. There's only one catch: Gellar wants to kiss Marcy on-screen.
Marcy misunderstands this somehow and, after going out to a bar with Gellar and downing a few drinks, she proceeds to kiss her. Gellar pushes her away in shock, and proceeds to go on some spiel about how she thought kissing a girl on screen would make her be noticed for an Emmy, and she never actually wanted to kiss Marcy. Not exactly the most complex or well-written storyline, but at least we got to see Buffy the Vampire Slayer kiss a girl.
Verdict: This is some meta reality for you, folks. Sadly she never did get that Emmy nomination for Buffy...