A bit of a mess of a human being/animal, often very fat and squat. A bit of a sexual predator, the wagaboo will often throw itself upon its prey at any given opportunity. It will accept no resistance, and will persevere until its prey is broken down with no defences left. This can also be referred to as the shagaboo, the shagamama and the shamu. On nights out the wagaboo will be the most drunk, trying to get onto all of your friends whilst screaming outs it mating call, which sounds a bit like, "worrgghhhhhhh". It will then make up stories and excuses to try and sleep in other peoples' beds. Beware of the wagaboo.
That fat girl who tried to get onto you last night whilst you were out, she was wailing "I LOVE YOU, WORGHHHH". and then at the end of the night the wagaboo started crying because she didnt have enough money to get a taxi home, in the hope that out of the goodness of your heart you'd let her stay there.