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"

Billing
A doctor and a lawyer were talking at a party.

Their conversation was constantly interrupted by people describing their ailments and asking the doctor for free medical advice.

After an hour of this, the exasperated doctor asked the lawyer, "What do you do to stop people from asking you for legal advice when you're out of the office?"

"I give it to them," replied the lawyer, "and then I send them a bill."

The doctor was shocked, but agreed to give it a try.

The next day, still feeling slightly guilty, the doctor prepared the bills.

When he went to place them in his mailbox, he found a bill from the lawyer.