[Torgo]

The variety of banana (Gros Michel) that was commonplace when the "slip on a banana peel" comedic device was invented was a different breed than the one that is commonplace today (Cavendish.) The Gros Michel peel was reportedly very slippery.

[soperj]

as an addendum to that, the reason you don't see Gros Michel today is because "Panama disease" (a wilt fungus) wiped out most of the plantations in South America/Africa. You can still find Gros Michels in Thailand today. Someone should write myth busters, maybe they could import a gros michel to test it.