From the Super Mario Wiki
A Stink Bob-omb is a Bob-omb seen in the Super Mario World episode "Born to Ride". During the episode, Yoshi wanted to join The DinoRiders. However Yoshi needed to pass a few tests to join the gang. One of the tests was throwing a Stink Bob-omb at one of the houses in Dome City. Yoshi was hesitant to throw it, so Lulu, a member of the DinoRider gang, threw it for him. After that, the Cave People inside the house get out.
A Stink Bob-omb does not explode like regular Bob-ombs and instead releases stinky gas. Stink Bob-ombs are obviously based on "Stink Bombs". They look like regular Bob-ombs.