The phrase "big whiff" refers to a situation where someone completely misses or fails at something they were trying to do or understand. Full definition
Obviously, my (and virtually everyone else's) biggest whiff last season was, well, another freshman - heavy Kentucky team, who went from the No. 2 overall seed on November 9th to the NIT. (sbnation.com)
This leads to some of the film's biggest whiffs on jokes. (indiewire.com)
In fact, if you see someone taking a big whiff of a newly popped cork, you might feel a little embarrassed for them - as was the case recently when a waiter at a fancy restaurant made a big show of sniffing my cork for me like it was a newly found truffle! (inc.com)