Can you actually do something with the RageCandyBar in Heartgold?

Question

Nuff' Said

Answer 1

Give it to the Man in the Underground Path

Source: Experience

Answer 2

The RageCandyBar appears in a similar capacity in HeartGold and SoulSilver as it did in Generation II. It is available in Mahogany Town only, but this time is a key item. This prevents the player from trading it to Pokémon Diamond, Pearl, and Platinum, where data for the item does not exist. The RageCandyBar is not a healing item in these games; instead, it is a key item that may be exchanged with a non-player character in the Underground Path (Routes 5-6) for TM64 (Explosion).
In this version of the game, the man blocking the way east will still sell the RageCandyBar after the Team Rocket invasion is foiled (instead of the lady in the shop, as in Gold and Silver). However, he will refuse to sell more than one.

Source

Answer 3

Yes. You may trade it for the TM64 Explosion with a man in the Underground Path.

The RageCandyBar appears in a similar capacity in HeartGold and SoulSilver as it did in Generation II. It is available in Mahogany Town only, but this time is a key item. This prevents the player from trading it to Pokémon Diamond, Pearl, and Platinum, where data for the item does not exist. The RageCandyBar is not a healing item in these games; instead, it is a key item that may be exchanged with a non-player character in the Underground Path (Routes 5-6) for TM64 (Explosion).

In this version of the game, the man blocking the way east will still sell the RageCandyBar after the Team Rocket invasion is foiled (instead of the lady in the shop, as in Gold and Silver). However, he will refuse to sell more than one.

http://bulbapedia.bulbagarden.net/wiki/RageCandyBar