dotdotdot is the oral form of "..." People who talk as if they were in a chat room in real life use this word for expressing how stupid their friends are or for saying something stupid and pointless and should be slapped for even talking like so.
It can also be said as "dot-dot-dot" but the odds people these days are going to bother saying "dash" for the "-" are incredibly low.
Dan: I LIKE TO DIP MY BREAD IN COTTAGE CHEESE!
Mandi: LIKE OMG THAT IS SO KEWL!
Dan: U R GHEY!