He grunted aggressively and without warning, a stiff gust of stinking gas blasting forth into the ill-prepared faces ahind his colono-rectal pipework and causing not one but two of them to wrinkle in disgust before vomiting, albeit only into their closed mouths, leaving them able to tidily dispose of the chunder out of the window in one case and, after an undignified struggle, back down their scalded gullet in the other.