When pigs fly is an idiom. It means something will never happen. For example:
"Do you think Tom's going to look for a new job."
"Yeah, when pigs fly!"
That means the speaker thinks Tom is never going to look for a new job.
ANNABELLE B-BAUMANN, Communication Coach
"Annabelle I've learned alot from you .....with your friendly art and your diversified lessons... it is never boring!!!" -Doris, BASF
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