What is Mexican Handshake?
1.
A strange form of masturbation involving squatting on the ground with flat feet with your knees held tighly to your chest. You arm must then go around one of your legs to reach the required organ.
Often done furiously and sometimes in public
I`m off to the park for a Mexican Handshake
See
2.
the act of greeting someone by grabbing and shaking one's croutch
After a long separation, Paco quickly greeted me with a mexican handshake.