A girl puts a lemon on your dick and then proceeds to jack you off. Then, the girl takes the lemon off and sucks your dick. However, it sucks for the girl because your dick has become exceedingly sour, resulting in an unsatisfying experience for the girl.
I gave Derek a lemon job last night, and it was the worst experience of my life. It was so fucking sour.
A girl places a lemon on a guy's penis and proceeds to give him a hand job using that lemon. Then, the girl takes the lemon off and gives the guy a blow job. However, the blow job is exceedingly unsatisfying for the girl because the lemon has caused the penis to become very sour and acidic.
Natalie gave me a lemon job last night. It felt great except she kept having to stop every two minutes because she claimed my dick was too sour.