Non-street inserts Oscar has appeared in

[muppet maniac]

The ones I know of are:

*Do De Rubber Duck
*I'm Sad Because I'm Happy
*Game show with Guy Smiley(he was there with some old lady...something about an old cloth?)

Also, there was an insert from 1969 that had him, along with Bert, Cookie, the purple monster from the "Monster Father and Son" sketch from The Ed Sullivan Show, and a few others. Saw this pic somewhere.

Any others?

 

[TotallySpiesFan]

Ernie & Bert: Chocolate Ice Cream (1970)
This is Your Life: Sneaker (1984)

 

[Pug Lover]

C is for Cookie

 

[GonzoLeaper]

Hmm, they never had Oscar in any of those sketches where the Muppet interacts with young children, like they did with Grover and Kermit, did they? I just started thinking that it would be pretty hilarious to see that, considering Oscar's grouchy nature!

 

[Dantecat]

He also was in The "Singing in the Shower" Skit.

 

[Boober_Gorg]

He also appeared in this segment where a trash can was drawn (slowly), then the word CASA appeared on the can. He popped out of the can and said "A grouch's can is his CASA."

 

[SesameMike]

There was also this 2-part skit in which Oscar appeared in E+B's apartment, though I don't think Bert was in this one.

Ernie was desperately rummaging through his things in search of his Rubber Ducky. Oscar suddenly appeared, and offered to buy Ernie a new one. In the second part, Oscar brought in this tall, ugly duck figure, that made an awful "auuuuuuu" sound when you squeezed it. Ernie was dissatisfied with the item, but then he finds his real ducky (hears a squeaking sound when he sits). Each are convinced that they have the better toy.

 

[SesameMike]

Don't know if this counts, but there was the cameo that Oscar made in the movie "The Great Muppet Caper". He was even credited to the (then) CTW.

There were also a handful of times that Oscar was mentioned off-street.

When E+B's apartment was messy, Bert orders Ernie to clean up or else he'll move in with Oscar, saying his can was neater than this place.

Also, one of the oldest, if not the first, "People in Your Neighborhood" song skits mentioned Oscar. Before the music began, Bob was chatting with two Anything Muppets, going something like this:

Bob's first question was: who delivers the milk?
AMs: The cow.
Bob: No, the cow gives the milk...
AMs: The farmer.
Bob: No the farmer milks the cow...

Bob's second question was: who takes away the garbage?
The AM's offered responses of "litterbugs" and "Oscar"

The correct answers of course, were the milkman (dated as that is nowadays) and the garbage man ("He'll always take your trash away... and I'll make sure your streets are clean"), who appeared with a mini-metal trash can.

 

[muppet maniac]

Also remembered one Ernie and Bert sketch about a blackout on Sesame Street, and Ernie decides to call someone on the telephone...who ends up being Oscar. He yells at him and "tries to make sure that whoever's calling doesnt get any sleep for a week"

i think scenes on the street without human performers also count. Ones I know of are:

*The Count constantly knocks on his trashcan to count how many times Oscar says "no"?(Ive seen this on Plaza sesamo once, and thats how much i understood whats happening

*I love trash(both versions)

*We're a couple of grouches

*Oscar reads a grouch story to Irvine: Snow Grouch and the 7 dwarves

*Dr. Nobel Price shows him a tiny metal trashcan he's invented, which contains party decorations and confetti coming out if it when opened(saw it on Plaza sesamo as well).

...if there are others, let me know

 

[SesameMike]

There's also:

• "Alphabet game", with Oscar and Grover. Grover says nice words, like "A is for Apple", while Oscar picks ugly ones like "B is for Blecch". (Yes, I know, B is also for Bump, as in thread.)
• "Oh show me the way to go home", lamented this cow who was trying to find a home. After being kicked out of at least two unsuitable (probably one-off) locations, he shows up at Oscar's can. Oscar angrily explains that his can is no place for a cow. Eventually, our bovine friend is welcomed at a barn -- by another cow.
• There was this one sketch that began on the actual set of The MacNeil/Lehrer Newshour, with the host doing a segment on small-business owners. The businessman he selects first is Oscar the Grouch, and interviews him on the big screen (green screen?) Oscar opened an ice-cream parlor at his can where all the flavors start with S. He rattles off a list of unlikely flavors such as "spare rib", and probably "sardine" and/or "spinach" as well. The host said "If I may editorialize a little, express my own opinion, I think your flavors are yucky!"