The ornamental design for a frying pan, as shown and described.
FIG. 1 is a top perspective view of a frying pan showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side elevational view thereof; and
FIG. 7 is a right side elevational view thereof; and,
FIG. 8 is another top perspective view thereof.
The broken line showing of the frying pan in FIGS. 1-8 are included for the purpose of showing environmental structure and form no part of the claimed design.