Grease trap, which showers you with grease when triggered, greasing your wielded weapon and giving you slippery fingers and several turns of fumbling. Occasionally, your armor may get randomly greased.

May drop a can of grease with 0-2 charges when untrapped.

If #3671 (greasy floor) is implemented, the grease trap may automatically replace itself with the greasy floor trap or terrain as part of its effect.

If an aklys is tethered to your hand when wielded, you shouldn’t be able to drop it due to slippery fingers or fumbling.

If you fall downstairs while fumbling, you may land on a monster that was already occupying the upstairs of the level below, damaging them proportional to the weight of your armor and possibly reducing the damage you took from falling down the stairs.

It is impossible to multishoot anything when you are fumbling or have slippery fingers.

If you walk over a banana while fumbling, you slip on it, making a lot of noise and destroying the banana. (This won’t happen if the banana is hidden under some other object on the square though).

A monster spell (or perhaps some esoteric monster damage type) that makes you intrinsically fumbling for some time.

Break the fumbling intrinsic into fumbling (only for hand-related things, conferred by fumble gloves) and stumbling (only for foot-related things, conferred by stumble boots).

Valkyries always get the snow boot bonus while walking on ice (i.e. they never stumble), even if they aren’t wearing snow boots.

When an imp says “Look! Thy bootlace is undone!”, he might tie your shoes together and cause you to fumble for d10 turns.

When attacking into a pit or falling while fumbling and wielding a pointy weapon, you have a chance of falling on your weapon.