Testing the Love Interest

So, you're suffering from Unrequited Love, or you don't know you're in love with your best friend, and you're on a date with someone else. Suddenly, a thought jumps to your mind "let's do that thing I love to do with my best friend/UnrequitedLove." You know the thing, that quirky game or activity that you participate in with that special someone. Related to, and sometimes involves, the Test Kiss.

This is a character's way of testing the relationship to see if it can work, even if they don't know it yet. If the date fails this test (which they usually do) they are never seen again.

Commonly used in romantic comedies or teen dramas, this trope is usually a quick and easy way to show that a person cares very deeply for their best friend/UnrequitedLove. It can also be used as a Love Epiphany for one or both characters.

A common variation of this trope is for the date involve playing a game in a way that is different than the normal way. Such as playing poker with Oreos instead of clay chips. Normally this will end with the date saying "this is stupid", or, "why can't we just do something normal?".

Examples of Testing the Love Interest include:

Anime and Manga

Mysterious Girlfriend X has Tsubaki almost try this with his "ritual" he and his girlfriend Urabe do with his previous crush, Hayakawa. He only really blurted it out out of unresolved feelings and it does somewhat lead to a small arc.

Film

Shows up in the film Made Of Honor, it is used as one of the clues that the male lead is in love with his best friend:

Tom: Ok, guess what I'm going to order
Random Date:...Why?
Tom: Just do it, it's a game, it's fun.
R.D.: Ok...A cookie?
Tom: No, be more specific, what kind of cookie?
R.D.: A really big cookie?

Spider-Man 2 has this when Mary Jane tries an upside-down kiss with her fiancé.
A variation of this occurs in The Wedding Singer. Drew Barrymore's character, Julia, tests out the name she will have if she marries her fiance, and she hates it. However, when she tries the name of Adam Sandler's character, she loves it. This is pretty much her Love Epiphany scene:

Julia: [into the mirror in her wedding dress] Hi. Nice to meet you. I'm Julia Guglia. Julia Guglia. Hi, it's nice to meet you I'm Julia Guglia.
Julia:(after a pause) Hello, it's nice to meet you. I'm Mrs. Robbie Hart. Robbie and I are so pleased you could come to our wedding.

Wedding Crashers: Claire does this with her fiancé. He reacts typically:

Sack: Can you ever get enough attention?

Live Action Television

Appears in Zoey 101, while Chase is on a date with Lola.

Western Animation

A purely platonic version happens on Arthur when best friends Francine and Muffy have a fight and break up. Muffy auditions a long list of her other friends and acquaintances for the role of "best friend", but when she finally settles on a candidate, she keeps suggesting things she would do with Francine, only for Binky to be completely uninterested.
In South Park when Kenny got Killed Off for Real the boys hold auditions for a new fourth member of their group. Butters wins, but they keep making him do "Kenny" type things and calling him "not-Kenny." He eventually quits.