Enter the codes at the Bonuses/Cheats menu, then activate them by pressing pause while you play and select them in the Cheats menu.
Carl wears Muntz's aviator goggles:
Enter AVIATORGOGGLES as a code.
Russell attracts all butterflies:
Enter BUTTERFLY as a code.
Carl jumps from the teeter totter to lift Russell end up in the air:
Enter CARLHEAVYWEIGHT as a code.
Carl creates multicoloured balloons when he jumps:
Enter BALLOONPARTY as a code.