To have the best intentions and try to be successful about something, and then suddenly miserably fail at that action altogether.
Wow! He was able to get back to the chick's dorm room making out on the side of the street, but then he completely pulled a moseby and ended up crashing in a dude's dorm room.
The absolute GOAT. Manager of the Tipton Hotel in New York City, he formerly managed the S.S Tipton and the Tipton Hotel in Boston. Played by PhilLewis a.k.a the best actor to ever grace Disney Channel with his presence (who incidentally killed a girl while being intoxicated in the 1990s). Mr. Moseby is often seen as uptight but in reality, he's incredibly compassionate and caring. He's 5' 6"
"Damn son you lookin' like Mr. Moseby with those knee socks."
When you tell a girl you love her inappropriately soon, like on the first or second date or during a first time hook up.
Unless she is the girl from swim fan she will most likely be freaked out by this declaration of love.
"Dude I messed up last night, I brought this cutiehome from the bar last night and accidentally Ted Mosby-ed her mid makeout session. She just said she had to go, as it was getting late and left."