A
jocular nickname for a
bacon cheeseburger, in some
Jewish circles.
In fact, a dish that contains any element that is not kosher is treyf, and it is absurd to talk about triple treyf. But a bacon cheeseburger - made from non-kosher beef, containing a pork product, and combining dairy and meat - is indeed treyf in three different ways.
For quadruple treyf, you can also cook it on the Sabbath or in a non-kosher pot.
For quintuple treyf, you can also eat it on a bun during Passover...