A gesture with raised pairs of fingers, when making a statement, to simulate quotation marks. It indicates that what is being said is ironic or otherwise not to be taken verbatim.
This originated in the USA. In 1989, Spy Magazine included this:
"When Bob and Betty describe themselves in these ways, they raise the middle and forefingers of both hands, momentarily forming twitching bunny ears - air quotes, the quintessential contemporary gesture that says We're not serious."
Air quotes have become a derided cliché.
The practice may not have been given a name until the 1980s, but there is a record of its being in use much earlier - in the July 1927 edition of Science:
"Some years ago I knew a very intelligent young woman who used to inform us that her 'bright sayings' were not original, by raising both hands above her head with the first and second fingers pointing upward. Her fingers were her 'quotation marks' and were very easily understood."
See also - air kiss.