汪 imitates a dog's bark (
汪汪 wāng wāng = woof woof). The slang began around 2014 on Chinese social media, riffing on
单身狗 (dānshēn gǒu, 'single dog') by replacing
狗 with the cuter, sound-symbolic
汪. Used jokingly and online, especially around
情人节 and
光棍节 (Singles' Day, 11/11).