Top definition
Australian slang for being too inebriated (drunk,tanked,etc...) to get an erection.
"Jeeze Mate, I could a shagged that sheila last night but got the Fosters Flop at the last minute"

"Fair dinkum, that's a worry!"
by Maur Schtupedschit June 22, 2005
Get a fosters flop mug for your barber Julia.