Merenade is a combonation of the two words "merinate" and "serenade." Basically it is when someone sings to their food. Some believe that this softens it up and makes it more dilectible. Others think that the food doesn't get softer, the jaw muscles just get warmed up from the singing so the food seems softer, when in fact the jaw is stronger and readier to eat it.
*As Forrest prepares to eat his muffin he starts to sing* "DJ got me fallin in love again!!!"
Lauren: "Forrest, stop singing to your muffin! You're an idiot!"
Forrest: *stops singing for a second* "I'm marenading it!"
Lauren: *gets annoyed* "do you mean serenade?"
Forrest: "No, merenade"
Lauren: "FORREST, YOU'RE RETARDED!"