Guying

Poking fun at. Mocking. Ridiculing. Showing scorn or satirizing. (Chiefly British, slightly dated.) It comes from the "Guy" in Guy Fawkes (figurehead of the failed 19th century gunpowder plot to blow up parliament). In the U.K., Fawkes is a figure of mockery and abuse to this day, and is burned in effigy all over the British isles every November 5.

He was so pleased that we kept coming up with new uses for his proposed invention; he had no idea we were all just guying the whole concept. He's a bit of a joke, really.