Green’s Dictionary of Slang

the breaking of wind.

1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: air biscuit n. Fart; botty burp. As in ‘Has somebody launched an air biscuit?’.
2005		Roger’s Profanisaurus in Viz Apr. 48: fart like a magican’s hanky n. A botty burp.