Another way of describing the phenomenon that is the Camel Toe, an American Tradition and Classic. When a women wears a pair of pants or shorts that shows her beefy pussy flaps actively swallowing the seam of her pants. It looks like when unstlyish dorks wear socks with their flip flop sandals.
In an office setting, coffee generally comes in little "sacks" of grounds that are proportioned to fill one pot. When one person puts in one package of coffee, he is said to have flopped a sack. Therefore, making coffee at work is to "flop a sack."