tumborn
Tumborn is actually made up of two combined words, tumblr + born. It basically means the date you created your own tumblr blog and started using it (the day you were born in tumblr). get it? :)
Girl 1: Hey, when were you tumborn? (means when did you create and started using tumblr)
Girl 2: Who, me? April 01, 2010!
Girl 2: Who, me? April 01, 2010!