The Didgeridoohickey is a homebrew magical item. Its appearance is not described, but is presumably similar in appearance to a didgeridoo, being a long pipe-shaped wood instrument. As magical items can shrink and grow in size with the user, this does not prevent it from being carried by Small individuals.
It gives Fire Resistance (halves fire damage) and Poison Resistance (halves poison damage).
A Didgeridoohickey is taken from the Chunky Bloke Pie Mine safe by the party, and later carried by Gadai.