Merlin is sometimes used to replace words such as sperm, cum, semen, jizz and spunk. Merlin is a male gamete or reproductive cell that is produced in the testicles. The word 'merlin' is a slang word that originated in the UK.
1. She was giving me a blowjob when I pulled out and covered her face in merlin.
2. When she walked out of the toilet, she had merlin on her lip.