A nice surprise when quaffing random NetHack potions, especially after building up poison resistance or getting whacked by certain monsters. Quaffing the uncursed potion restores one random statistic to its previous maximum amount (i.e. if Strength is chosen, and you started with 17 but got poisoned a couple of times so it dropped to 10, it'll go back up to 17). The blessed version restores all ability scores to their previous maximum values.

The cursed version does nothing at all ("Ulch! This makes you feel mediocre!"). Throwing the potion at a monster restores it to full hit points. Inhaling the vapors from a smashed potion restores one randomly-chosen ability score by one point (if the potion was blessed, all ability scores are restored by one point).