Boo [verb]

A small smattering of boos could be heard from the tiny crowd at the Superdome, as noted on the broadcast.

At one point an incomplete throw to Antonio Brown resulted in a stray boo wafting from the socially distanced crowd.

Cheers, boos and screams greet each new state projection, and crowds stick around until the wee hours, waiting for networks to make the call.

Fans are cheering Elon Musk’s speedster from the home side of the bleachers, and naysayers are blasting boos from across the track.

This is better than frightening them out of their skins by jumping out from behind a door and saying "Boo."

Sometimes I don't get around till ten or eleven o'clock in the great boo-black dark.

Even the most reckless of gambling junkmen could not be expected to dare much of an investment in such a peek-a-boo game as that.

When the doorbell rang, half an hour later, Mr. Fielding was on his hands and knees playing "peek-boo!"

"And say 'Boo' to naughty little girls who won't let me complete my diary," shouted Brand.

Later on, the "forward" vowel is gradually widened into the other vowels; exercises are sung on boo-ah, doo-ah, etc.