When getting into your bed at night and realize your child has decided to hide in the form of a sack of potatoes.

Large, beautiful breasts that are keep well consealed and initially appear to be much smaller and less impressive than they actually are until unleashed.

Me I am a sack of potatoes

As in the expression, "drop you like a sack of potatoes" which indicates that the aforementioned "sack" containing "potatoes" has been dropped at a greater velocity then that of an unladen swiss style sack.

The thigh/butt area of a woman who has so much fat and cellulose build up that the lumpiness resembles a giant sack of potatoes.