A staged wedding to bust dealers
As supposedly reported on CNN:

Undercover police, staging the wedding of "a drug kingpin's daughter", let it be known on the street that dealers were "invited" (i. e. Expected to attend).

The bride and groom were police, as was the band, bartender, and about half the guests. The band playing at the wedding was "S. P. O. C." (COPS, backwards), and the wedding went through the full ceremony, including the dancing afterward.

The long-sought dealers were arrested after the "band" took their break. The last song the band played before taking its break? "I Fought The Law, And The Law Won"

bad advice
Walking past the Royal Courts of Justice one day, a man spotted a friend of his sitting on the steps outside, sobbing loudly with his head buried in his hands.

"What's the matter?"

he asked of his friend, "did your lawyer give you bad advice ..?"

"No - it's worse than that," replied the friend between sobs, " he sold it to me..."