its a hybrid of ridonkulous (extremly ridiculous) a badonkadonk (a huge ass in comparison with a womens body)
In other words its a ridiculusly huge ass
ridonkulous + badonkadonk = ridonkabonkadonkulous
Alfie : damn! that girl has badonkadonk ! James : thats a ridonkulousbadonkadonk! Roger & Harry :NO U HO-MO-FOS! that girl is ridonkabonkadonkulous!
The fact that he owes 50,000 in student loans? That's ridiculous. The fact that he dropped out after one semester? That's ridonkulous. The fact that said 50,000 was spent entirely on Cheez-Its? That's ridonkadonk.