An oriental whip snake, spotted in Pasir Ris Park, Singapore. It was hanging motionless among the bushes, waiting for a lizard to venture within striking distance.
Its camouflage is excellent. I would probably have missed it, had it not been for another photographer who was already stalking it when I arrived on the scene. Sadly we did not see it hunt; it retreated into denser vegetation soon afterwards.
The common Bengali name for vine snakes is লাউডগা (laudoga, meaning "bottle-gourd vine"), and indeed, it looks very similar. The genus name, Ahaetulla, comes from Sinhalese, and means "eye-plucker". According to the Wikipedia article, one of its alternative names is "judgmental shoelace", which appears to stem from this meme.
And now for some Asian water monitor anatomy. I encountered this fine fellow in the Botanic Gardens.
Exhibit A: tongue.
Exhibit B: nictitating membrane.