If a potion of booze shatters in a sufficiently hot circumstance (hitting a fiery enemy, landing on lava or on the ground in Gehennom), it creates a fireball expplosion on its space.

Potion of hazardous waste: never randomly generated, but can be created as a possible byproduct of random alchemy. Its effects are unspecified.

Shattering a luckstone (presumably by rubbing it on a cursed touchstone, which should currently be the only way to bring this about) should bring seven years of bad luck, represented in-game by setting luck to -10.

Red light, a y that has an explosion attack that causes paralysis. This is a reference to red (traffic) lights in real life making you stop.

(There could also be green lights whose explosion gives a temporary speed boost, and yellow lights’ explosion could be expanded to slow the target as well as blinding it, but since this isn’t harmful to the target it’s a sillier idea.)

Chatting to a pet that is carrying an item picked up off the floor will command them to drop the item. The odds of them obeying depend on their tameness and apport.

Teleporting no longer checks to see if there is a monster present on the destination tile. Teleporting into a monster’s space has a chance of telefragging and instakilling it. (Though for fairness this should also happen to the player if a monster randomly teleports onto their space.)

A tinning kit’s weight is dependent on how many charges it has left, getting lighter as it is used to tin things. This could also be extended to other tools which have charges and are not magical, such as cans of grease.

Player status called Terrified: it acts like confusion and stunning in that it makes you move in uncontrolled ways, except that it pathfinds away from whatever is scaring you.

A magic trap that causes you to yearn for your distant homeland may instantly magic portal you to your quest home level (perhaps asking you first).