The Medicine Box offers 11 tips for giving a bad homily. Here's a sample, from Tip no. 4 ("Reach the young people"):
Do popular songs on the radio remind you of Biblical passages? Is there some way a blockbuster summer movie can be said to show God's forgiveness? Is Jesus maybe a little bit like Spider-Man?
If you answered "yes" to any of these questions, you're well on your way to developing one of the most popular techniques for delivering a bad homily: tailoring it to young worshipers by dumbing it down with a plethora of poorly thought out pop culture references.
When doing so, though, you'll want to remember to keep those references vaguely out of date, so that anyone in the pews who might possibly be reached by such a tactic will instead focus on their mirth at your use of "X-Files" terminology.
You'll also want to keep the metaphors as tortured as possible. Popular culture, like all Western culture, is indeed filled with allusions and references - sometimes self-aware, sometimes not - to Christianity. Instead of going for the obvious ones, though, you'll want to instead explain how Jesus is like Buffy the Vampire Slayer, and the vampires are sins and they're not really being slain so much as forgiven, and of course Jesus is not a woman.
You can read the other ten tips at the Medicine Box. (And yes, bad homily anecdotes -- no naming names, please -- are welcome in the comments box below.)