When a woman has so much pubic hair, lice and other gross, disgusting things that the partner has to get through a "bushtucker trial" before engaging in Oral Sex.
Bob - "Did you lick out that girl last night?"
Steve - "Yeah, I had to go through a Bushtucker trial first!"
A pubic area with alot of hair , AKA 'bush' - hence the name. Someone who obtains a bushtukka not only has alot of pubes but a very gross style about it. The world rolls of the tip of the tongue much better than just 'bush' becaue the 'tukka' allows further disgust.