(n) or (v)The act of two men (gay, bi, straight) laying "side-by-side" and giving each other "hand jobs" and/or masturbating them selves. With three people this could be referred to as "skiing". See other terms such as Ohio State Cheerleader for examples.
"Wow Nate did you hear about Joey and that random doing a 'side-by-side' in Arizona ?" , " I always enjoy a good "side-by-side" at the fiesta bowl. "