From Lost Temple Traders:
"On one of our more peculiar voyages, we came upon the most delightful sound. Sister Sirens Swam Ashore and Singing us to Sweet Serenity. They were as beautiful as they were deadly. Luckily for us, we do not listen very well, and survived the encounter with our lives. Will you heed their call?
Sister Sirens are limited to 250 pieces. These mugs are sculpted by Gilbert Lozano and produced by Munktiki Imports."
*There is a blue version as well.