I'm pretty sure it's hall of the mountain king.
I dont know if it's from Peter and the Wolf or not, wait
No, it's def Hall of the Mountain King.

That's
Peter and the Wolf
.

I beleive that its "The Hall of the Mountain King"

So does anyone know the name of the classical piece of music that plays while einstein and his dad are in the shed drinking beer? that scene there, and the subsequent splitting of the beer atom, make me crack up all the time. any help is greatly appreciated

i'll drink to that!

so how bout that splitting of a beer atom, eh?

No, drunk_bastard_jb is right; it IS "Satisfaction" by The Rolling Stones. It is credited at the end of the movie.

Yahoo Serious stuck to Australian Pub rock throughout the movie
Paul Kelly - Dumb Things has a very similar brass sound to that i hear from his Violin
dum dum da da da dum dum,
if anything its probably a variation of a song on the soundtrack
Playlist files:

1. Yahoo Serious - Rock and Roll Music (0:28)
2. Mental as Anything - Rock and Roll Music (3:00)
3. The Saints - The Music Goes Round My Head (3:43)
4. Yahoo and Lulu - Who Can You Trust? (Main Theme) (0:29)
5. Paul Kelly and the Coloured Girls - Dumb Things (2:42)
6. Big Pig - Hungry Town (3:04)
7. Icehouse - Great Southern Land (5:10)
8. The Song Company - Great Big Brain (0:35)
9. Yahoo Serious - The Tasmanian (0:07)
10. Models - I Hear Motion (4:22)
11. Yahoo Serious - Theory of Relativity (1:14)
12. The Stems - At First Sight (4:00)
13. A Fist Full of Scientists (1:18)
14. The Lime Spiders - Weirdo Libido (3:38)
15. Yahoo Serious - Young Einstein Pacifist (2:10)
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I believe it's "I Can't Get No Satisfaction" by "The Rolling Stones", although I could be going insane.