The ornamental design for a vented sock, as shown and described.
FIG. 1 is a left side elevational view of the vented sock shown lying flat showing our new design; and,
FIG. 2 is a right side elevational view thereof shown lying flat.
The broken line showing of a ribbed top in FIGS. 1 and 2 is included for the purpose of showing environmental portions of the vented sock and forms no part of the claimed design. ps The stippled strip on the sides of the socks represents a change in material.