Bubble gum for your ass. Bubbles can be blown by sticking the gum up your ass and slowly farting, being careful not to let one rip too strongly. Popped dubble bubbles can be both sweet and smelly, with emphasis on the smelly.
Ernie purchased a Dubble Blubble at the candy store. He went out back and shoved it far up his anus and squished it around. Then he slowly flatulated, causing a brown and pink bubble to expand out of his asshole. When the blubble popped, it smelled like a weird combination of sugar and shit.