Opposite of cibai (vagina)
It is widely used for express ones anger or frustration.
Often accompanies by cibai in a sentence.
"Lanjiao lah, you think Beckham is god meh?"
"What lah, you don't have lanjiao ah, go chase her lah!"
"Eh lanjiao-kia, siam tam pok lah, people watching tv wah!"
All the above conversations are in Singlish