blow a raspberry
To make a sputtering noise by pressing the tongue and lips together. It can be used to express either real or faux contempt, mockery, or displeasure, or as a playful gesture. The term originated with rhyming slang, in which "raspberry tart" was used as a substitute for "fart." Jacqueline blew a raspberry at Dave after he made fun of her new haircut. Tara loves hearing her baby boy giggle when she blows raspberries on his tummy.
blow a raspberry
make a derisive or contemptuous sound with your lips. This expression is from rhyming slang, where raspberry tart means a fart.
1996 Observer It is unthinkable that, this close to a general election, the party is going to blow a raspberry at its leader.