Caviar has a bit of a reputation as an aphrodisiac, and that has led to the existence of a bawdy song about these fish eggs. It is to the tune of a song called "Reuben, Reuben I've Been Thinking," which I have never heard of in my life.

The chorus of the song goes like this:
Caviar comes from a virgin sturgeon
A virgin sturgeon's a very rare fish
A virgin sturgeon needs no urgin
That's why caviar's my favorite dish!

The verses all start with the line "I gave caviar to X," with X being a person, and then three more lines describing the fun that ensues.

Here are two example verses I see floating around the Internet:
I gave caviar to my girlfriend,
She was a virgin through and through,
Since I gave my girlfriend caviar,
There ain't nothing she won't do.

I gave caviar to my grandpa,
Grandpa's age is ninety-three,
Last time that I saw grandpa,
He's chased grandma up a tree.

Now my personal experience with seeing this song performed was by the Wench Singers at the New York Renaissance Faire where I worked this summer. The wenches were all responsible for their own verses (as they sung the chorus together, then a verse would be sung solo to someone in the audience) and were always coming up with some fuckin' hilarious lines involving "hunters shooting their load" and Robin Hood's Greenwood being "where more than plans get laid." Most of the fun of the song is in making up the new verses. Unfortunately, I only remember one of them fully right now, but here it is:

I gave caviar to a Puritan,
It is quite a delicacy,
Delicate is not that Puritan,
He praises God by spanking me!

Should you ever visit the NYRF, I would advise you to check the Wench Singers out. :)