The act of confessing feelings for a girl way too early.
This term comes from the show How I Met Your Mother, after
the main character Ted Mosby tells a girl he's
interested in that he thinks he's in love with her after their first date.
Later in the series, the term "Mosbying" is coined after Ted's friend Barney hooks up with a girl at a party, doesn't want to see her again, and tell her he's in love with her to make her want
nothing to do with him.