The ornamental design for a forefingerguard, as shown and described.
FIG. 1 is a top plan view of a forefinger guard according to the present invention.
FIG. 2 is a bottom plan view of a forefinger guard according to the present invention.
FIG. 3 is a right side elevation view of a forefinger guard according to the present invention.
FIG. 4 is a left side elevation view of a forefinger guard according to the present invention.
FIG. 5 is a rear view of a forefinger guard according to the present invention.
FIG. 6 is a front view of a forefinger guard according to the present invention; and,
FIG. 7 is a bottom perspective view of a forefinger guard according to the present invention. The hand of a user shown in broken lines illustrates the environment in which the claimed design is worn. The broken-line subject matter forms no part of the claimed design.