asshot spankable means some girl is so fine you just want to hit that all night long. Meaning she looks very very very very very very very very fuckable.
I don't believe it! Excited exclamation of disbelief or excitement.
Interviewer: "Well Mr Jones, everything seems to be in order and we are delighted to offer you the job"
Mr Jones: "Well spank my ass and call me Sally!"
Interviewer: "......"