Complete the Chamber 4-9 without knocking over any turrets

Blow up a test chamber sign

Take a shower under one of the gel cleansing fields

Deplete the conveyors' supply of Weighted Storage Cubes

Stare at Conly's mannequins for a really long time

Smear your dirty fingers over Aperture's beautiful glass

Fling in an endless loop in Chamber 4-11

Deplete the gel supply in Chamber 4-11

Solve the Chamber 6-2 twice

Complete Chamber 5-1 without destroying any turrets

Solve Chamber 6-6 the boring way

Solve Chamber 6-6 the fun way

Get the ball in 4-10 to land perfectly in the socket