Flip Flop Size 13

flip flop
interchange: reverse (a direction, attitude, or course of action)
An abrupt reversal of policy
A light sandal, typically of plastic or rubber, with a thong between the big and second toe
reversal: a decision to reverse an earlier decision
A backward handspring
a backless sandal held to the foot by a thong between the big toe and the second toe

size
Extensive dimensions or magnitude
(used in combination) sized; "the economy-size package"; "average-size house"
The relative extent of something; a thing's overall dimensions or magnitude; how big something is
the physical magnitude of something (how big it is); "a wolf is about the size of a large dog"
Each of the classes, typically numbered, into which garments or other articles are divided according to how large they are
cover or stiffen or glaze a porous material with size or sizing (a glutinous substance)

13
thirteen: being one more than twelve
thirteen: the cardinal number that is the sum of twelve and one
Year 13 (XIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar.