A phrase some Christian teens and children use in place of "Goddam," because they don't want to use God's name in vain. Some non-Christians (or Christians who use God's name in vain) use "Bob damn" when their friend's who don't use God's name in vain lecture them on saying "Goddam."
Derryc: "Hey, man, we have a test in Mrs. F's class. Did you study???
Erryc: "What...???!!! Ughhh!!! Bob damn you, Mrs. F!!!
Kyra: "Goddam!!! I just got mascara in my eye!!!"
Kyra: "Oh, sorry, M. I meant, Bob damn!!!"