Yellow stuff

My humans were eating yesterday, so I went over to see them, or to see what they were eating.

I sat down next to them and pawed towards their plates, until they said 'no, Clive'.

My male human gave me something green to sniff. I didn't want it.

My female human gave me a bit of meat. It was beef. Mmmmm.

My male human gave me a round thing to sniff. It didn't smell of meat. I left it.

Then I pawed at a yellow thing on the table. 
My male human held it out for me to sniff.
I sniffed it and ... whooooop. Too strong. Catty nose spasms.

I did a catty-choo, then another catty-choo, then another catty-choo.
Then I had to do catty headshakes.

What was that yellow stuff?
Why would humans have it with food?
Why did my human hold it out for me to smell?
Idiot.