Bob-ombs first come into play in the Mario Kart series in Mario Kart 64. They were not used as an Item, but are sprawled out across the Track in multiplayer only. Also, in the Balloon Battle mode, if a player died in at least 3-player, they were transformed into Bob-omb Cars that can ram into surviving players.
In Mario Kart: Super Circuit, these bombs just spectate the award ceremony.
They come back in Mario Kart: Double Dash!! as Wario and Waluigi's special item. Petey Piranha and King Boo also can possess this item due to being able to receive any special. Since then, Bob-ombs have been an item in the succeeding games, open to every character. A mode centered around the item, Bob-omb Blast, was also introduced in this game.
In Mario Kart 8, Bob-ombs will now walk around the track whilst ticking away. Previously, they only sat on the track waiting to explode.
The Bob-omb is an offensive Item. It can be thrown ahead of the user's kart to try to knock over the opponent up ahead. If no one is near the Bob-omb, it will take about four seconds to detonate automatically. However, if a racer is near one, or if it is thrown and lands directly on a racer, it will blow up right away. The blast radius is about 3 meters and throws any kart up into the air (similar to a Spiny Shell.) However, if a racer drives into the explosion, they will simply spin out.
The Bob-omb can also be dragged and dropped behind the kart. Using it as a shield against other Items such as a Green Shell or Red Shell is a bad idea (really bad idea) because it will blow it up right behind you unless you drop it before the item hits, requiring good timing in order to guard with one.
While the Bob-omb, as noted, can be used as a defense against Green Shells and Red Shells, it is rare to have a Bob-omb in first place. Should you need to guard with it, however, simply drop it behind you right when the shell is about to come down on you, and it will destroy the Item (extremely helpful technique!). However, the Bob-omb's explosion affects people in use of a Mega Mushroom, resulting in a giant flipping kart.
- Oddly, the ticking sound in Mario Kart 8 is the sound of them winding up instead of winding down.