How about the Bachelor Party episodes? 1. The man promises not to have strippers, best friend hires em anyway, woman finds out and gives silent treatment/cold shoulder.
2. The man promises to be good, happens upon bachelorette party with male strippers and wild goings ons and is comically outraged.
3. Cops arrive and are mistaken for strippers. (Reno 911 brilliant exception)
Ratings are dropping? Have a baby! Ratings are really dropping? Have twins. Of course, the kid(s) will rarely be seen and will age magically in about a year.
Speaking of pregnancy, not a cliche per se, but “let’s hid the baby bump” is another sitcom practice. Cosby with Clair and Denise. Seinfeld with Elaine (twice). Kate & Allie with Kate. The Nanny did a great satire scene of this when first hiding the pregnancy of Lauren Lane (C.C. Babcock)
Any woman who’s asked to be a bridesmaid will have to wear a truly horrific bridesmaid dress. Apparently all brides are colour-blind and sadistic.
In sitcom world, all weddings last exactly two minutes. There is no ceremony or music (other than the marching-in tune); the priest/minister/rabbi starts right in with the “We are gathered here today…” And magically, none of the guests mind that they flew in from out of town, had to pony up for a hotel and a gift, and the whole thing’s over in two minutes. Of course, that’s if the wedding isn’t stopped at the very last minute…
Oh, and people in sitcom weddings always write their own vows, too.
You forgot the biggest cliche about weddings–they never go off without a major hitch. Somone tries to stop it or the wrong person is there or the bride goes into labor. Or something.
Two people have to deliver bad news to someone else. Person A volunteers to give the news: “Mr. Smith, we have something to tell you. You see, it’s…well…um…the thing is…[pushing Bob to the forefront] Bob has something he wants to tell you!”
On-the-phone cliches:
Person is yelling at the unseen person on the other end of the phone: “I don’t care! Yeah? Same to you, jerk! [pause] OK, see you later, Mom.”
Person is trying to sell something over the phone: “Are you sure you don’t want to buy some life insurance? It’s very important! [pause] Well, little girl, is your mommy home?”
Person is trying to (again) break some bad news: “Sally, you have to listen to me. I know you were really counting on that vacation, but I didn’t get the promotion, and…hello? Hello? Are you there? Hello?” (And then, in case you didn’t get it, the character may optionally add, “She hung up!”)