When you are stuck on Urban Dictionary for hours reading random definitions.
Jack- Dude! You missed the wedding!
You- I know, I was totally in an Urban Loop before I knew it 3 hours had passed.
Similar to a youtube loop, the urban loop is when you are stuck in an alternate dimension for a long period of time going from one interesting/funny definition on Urbandictionary.com to the next.
Girl: Where were you yesterday!? I waited for you for 2 hours at the movies!
Guy: Oh wow, I'm really sorry! I was stuck in an urban loop!