From Wiktionary, the free dictionary
wee woo
- (informal) The sound of a siren.
2005, Mark O'Hare, Various, Terry Collins, Annie Auerbach, Deep-Sea Tales: 6 Salty Sea Stories, Simon and Schuster, →ISBN, page 145:“Put on your siren,” SpongeBob told Patrick. […]
Patrick […] whispered, “Wee...woo...wee...woo...wee...woo...”
2007, Jessica Scott Kerrin, Joseph Kelly, Martin Bridge: Sound the Alarm!, Kids Can Press Ltd, →ISBN, page 105:“Want to hear the siren, boys?” […]
They nodded eagerly.
Wee-woo! Wee-woo! went the siren.