In 1992, when NBC wrangled Kramer out of “Seinfeld” and into a crossover episode of “Mad About You,” it helped explain the mystery behind how he could afford his apartment.

In the Season 1 episode titled “The Apartment,” Paul Buchman (Paul Reiser) moves on from his past by giving Kramer his bachelor pad on West 81st Street with no strings attached.

The source of Kramer's income has long been a subject of intense scrutiny (at least among fans; the other “Seinfeld” characters are more or less indifferent).

Plenty of dark Kramer theories abound online — that a bad marriage left him a shut-in or that he's living off his disability checks from his time as a Navy SEAL.

But for a number of “Seinfeld” fans, the “Mad About You” crossover cameo is the most clear-cut answer to Kramer's rent check woes.