Tonight, our screens are overrun by the strange parallel universe that is the incestuous world of American sitcoms. Inviting celebrities to star as one-off characters, or even regulars, is acceptable practice, but tonight we get celebrities appearing both as themselves, and as characters they play in other sitcoms. It is all a bit much.
In Mad About You (Pearl, 6.50pm), Jamie and Paul plan their first night out together post-Mabel. The night is fraught with disaster not only because Paul has collected the wrong dry-cleaning from the store, and ended up with David Copperfield's trousers, but because Jamie is paranoid about leaving the baby for the first time.
As more experienced parents eventually realise, as long as you have not hired Louise Woodward as a baby-sitter, leaving a newborn is actually easy, they just sleep a lot anyway.
Jamie is not an experienced parent however, and so of course she worries.
Lili Taylor plays the baby-sitter, Arly, who has to put up with Jamie's nerves, and Lisa Kudrow from Friends, makes a guest appearance not as Phoebe, but as Phoebe's horrid twin, Ursula.
Then later in Seinfeld (Pearl, 9pm), Courtney Cox from Friends also turns up. Not as Monica, but playing one of Jerry's girlfriends, Meryl. And there is another dry-cleaning fiasco plotline, which suggests the scriptwriters of NBC sitcoms have a lot of bad experiences with dry cleaners.
Meryl starts the episode by pretending to be Jerry's wife in order to get a dry-cleaning discount, so we know straight away she is not going to last very long.
