Will flip upside-down when Isaac tries to collect it. Afterwards, it will get stuck on the ground, unable to be picked up unless blasted off the ground with an explosion. Bumbo and Bum Friend are unable to pick this up; they instead hover over them, attempting to pick them up.
A Level 4 Bumbo will drop bombs in an attempt to pick it up.
Unlocking Sticky Nickels is strictly speaking a downgrade, as they replace normal nickels, though the sticky ones are rare enough to not make a severe difference.
Although Edmund McMillen has stated that Sticky Nickels should replace pennies,[1] this is not how they are actually implemented.
Ultra Greed and his statue cannot pick up Sticky Nickels until they have been unstuck by an explosion, thus negating some difficulty from the fight.
During the Ultra Greed fight, if a Sticky Nickel drops, Ultra Greed will be continuously drawn to it.
Sticky Nickels visibly stick to the ground upon spawning, making them easier to distinguish from ordinary nickels.
In the unlikely event that a Sticky Nickel is present during the Bumbino fight, the boss will try to pick the coin up in futility, making him distracted and thus negating much of the difficulty of the fight.
Sack Head can cause a Golden Penny to spawn a sack instead of another Golden Penny.
The probabilities in the table refer to the kind of coin that is generated by the game when a coin is spawned with a sub-type of 0 (i.e. a random coin).
It's the Key - Defeat The Lamb without taking Hearts, Coins, or Bombs through the entire run. Letting certain familiars (e.g. Bum Friend, Dark Bum, Bumbo or Lil Portal) or bosses (e.g. Bumbino) pick up the consumables fails this condition as well..
Golden Razor - In a single run, obtain 99 Coins, then spend all of them.