A reference to being a ladies' man or player; usually self proclaimed.
Farmer John is a character who is most commonly found on a farm around livestock, including but not limited to chickens. Hence the term Farmer John may be used in reference to "gettin chicks"
Rapper Yellaboi coined the term in his 2010 song "Honeys to Blow"
"They call me FarmerJohn (why?) Becaue I get chicks"
You eat 3-4 cans of whole corn, or one to two ears if your that kind of person, one day before meeting up with your dream girl. When your girl goes to philash you, say "hold on bessie your getting a farmer john today", you start "plowing" her from behind. Then when the mood is right, flip her over and let out your corny top soil in a nice row on her chest. Poke a few holes in the soil and make sure to plant enough man seed for a good harvest.
My girlfriend wanted to go out dancing, but she had to stay home and wash off her farmer john.