A "Fat Sesh" is when one has a rather large bowl of the M and M chocolates, and a spoon. The person partaking in the fat sesh then will eat the M and M chocolates with the spoon.
The homosocial, nonsexual bonding between men from the age of 16 up where men discuss manly things in a masculine environment such as a dive bar, a house with a TV and beer pong table. The Bro Sesh may sometimes include, but is not limited to the use of tobacco products, recreational drugs, and alcohol.