It was during the 'Time Team' sketch.
As Bearded Geek 1 exclaims that he has made an amazing discovery- a small rock! Tony Robinson asks excitedly if is ia part of a "Roman Temple or Viking settlement?" Bearded Geek 1 replies with contempt "No Tony, this is clearly a Dilithium Crystal. It is used as the power source in the warp core of a Galaxy Class Starship, enabling it to travel between starsystems faster than light speed.....Of corse, I shall have to check my finding by watching Star Trek-The Next Generation tonight." Bearded Geek 2 replies-"As long as Babylon 5 is not on!". Bearded Geek 1 then exclaims-"Wash your mouth out!"
Make your own mind up as to weather it was favourable or not. I really liked the mention.