Prince Sang Nila Utama of the Sri Vijaya empire discovered the island of Singapore in the 11th century. On landing he spotted a strange beast having a lion's head and a fish-like lower half of a body, riding the waves of the sea. The Merlion was sculptured after the beast that Prince Sang Nila Utama saw.
There are unfortunately no records of how much rum (or rather rice wine. rice and 5 month old chicken feathers is a staple source of food for the royale family) there had been on the prince's ship or how much he had consumed before reaching the shore. We may also never know whether alternatives such as the merbadger, mercow or merhamster were passed up before settling on the final name.