Gandolf the Grey and the Balrog are driving down the highway. The Balrog is in too small a car and he's already pissed off. He tries to get by Gandolf, but Gandolf won't have it. He gets pissed as well, rolls down his window and yells "YOU SHALL NOT PAAASSSS!!!". A fissure opens in the highway and the Balrog drives right into it.
Flash later to young Gandolf (still with beard) and young Balrog in a classroom taking a test. The Balrog tries to copy off of Gandolf, and Gandolf yells "YOU SHALL NOT PASS" in his kiddie voice and the floor swallows up the Balrog.
::Insert similar scenarios here::
(Optional) - Later Gandolf and the Balrog are sitting next to eachother on a park bench. They look at eachother and kiss. Immediately cut to Legolas explaining to the elven princess that Gandolf was 'taken by both shadow and flame'.