The song was made famous by Lisa Kudrow's character in the very popular 90's sitcom, Friends.

Phoebe is an animal lover and vegetarian. She hates the idea of fur clothing (although ends up wearing a fur coat for part of an episode because she likes it too much). 

The show's running gag and one of Phoebe's trademark characteristics is her song "Smelly Cat," which she performs at Central Perk. 

The song is about a cat who is shunned by society because of its foul stench as a result of flatulence ("what are they feeding you?"). 

However Phoebe sympathizes with it because she can relate to being an outcast. 

Here are the lyrics:

Smelly cat, smelly cat what are they feeding you?
Smelly cat, smelly cat it's not your fault...

They won't take you to the vet.
You're obviously not their favourite pet.
You may not be a bed of roses,
And you're no friend to those with noses.

Smelly cat, smelly cat what are they feeding you?
Smelly cat, smelly cat it's not your fault!

- MornéJK