An intended easter egg programmed in by the original aLttP staff that can be accessed as a result of what is essentially a glitch. It can be set up in a number of places.
Dropping into the Houlihan room will grant the player 45 five rupee pieces for 225 rupees, making it an occasional stop for runners searching for 500 rupees for Zora. The Houlihan Room can only be accessed once per run.
For more information on the Houlihan Room, read the Zelda Wiki article on the Chris Houlihan Room.