A short line of cocaine

The indigenous Australian (Aboriginal) word for a discarded cigarette end that contains enough tobacco to be lit and enhaled.

Slang: A person, usually male, who is 'special', particularly clumsy while multi-tasking (ie talking and walking down stairs). Would benefit with the addition of protective padding, hence the name 'Bumpers'.

voluptuous buns

To "bumper" refers to the act of collecting food left over by others after a meal in a restaurant (total strangers) and eating it yourself, without concern for potential infection. You do it after they've left but before the bus boy has cleaned up the table.
People have various "bumper lines," i.e., limits to which types of food or drink they're willing to bumper.
True "bumpering" is done regardless of whether the bumperer has money or is hungry. It's a principle-based practice to avoid wasting food. But hunger or poverty can also be major motivators.

farting on a girls tongue while she gives you a rim job.

The part of a car that collides first in a front or end-on collision. (Americans use the word fender).