When Garry’s mom realized that mentioning her pet shop on his show boosted business, he eventually had to put his foot down. Undeterred, Ruth showed up on the daytime soap opera "General Hospital", as Gary and his friends watched from home, to give nurse Amy Vining and Dr. Tom Hardy the hard sell.

Making the crossover super-meta, Garry himself raced to GH to take home his mom, bumping into his own co-star, Ian Buchanan, who at the time also played GH‘s Duke Lavery.

It’s Garry Shandling’s Show Season 3, Episode 11

https://tvline.com/lists/weirdest-tv-crossovers-list-video-supernatural-bones/its-garry-shandlings-show-general-hospital/