Hi!
First and foremost, I used the search function for 'Goblin Hot Potato' and nothing came up so I hope this isn't a repost.
The Goblin Hot Potato from the Steamwheedle Preservation Society is like any other item you can throw to players, but it has a catch to it. That catch is that it will randomly explode sometimes on use and throw you in the air at different heights with a debuff that lasts either 7sec, 8sec or 30sec. (the lower the debuff timer, the lower you will explode, although the height on 7second debuff explosions can go pretty high sometimes.)
Using immunities (ex, ice block (haven't tested) hand of protection and divine shield) you can remove the debuff from yourself and then Goblin Glider instantly to get to areas. Some places I've used the potato exploision for with a Paladin friend to BoP me are
-Blackhand Mythic with 0/10mythic completed
-Iron Maidens Mythic with 0/10 mythic completed.
-Imperator Mar'gok Mythic with 5/7m cleared (sadly he doesn't actually spawn until Ko'ragh dies.)
-Outside of Grimrail Depot. (onto the terrain where the train is
-Outside of various different instances ranging from Vanilla-WoD
Currently the Potato is usable in raid and dungeon instances, aswell as anywhere in Azeroth / Outland / Draenor but I can't yet verify that it's usable in Battlegrounds
A side note: to buy and use the Goblin Hot Potato, you need to have atleast Honored reputation with the Steamwheedle Preservation Society and you can buy them in your factions Town Hall in Warspear / Stormshield from the rep vendor.