The ornamental design for a footballbag thereof, as shown and described.
FIG. 1 is a perspective view.
FIG. 2 is a front view.
FIG. 3 is a rear view.
FIG. 4 is a left side view.
FIG. 5 is a right side view.
FIG. 6 is a top view; and,
FIG. 7 is a bottom view.
The broken lines showing the bag strap and portions of the bag are for the purposes of illustrating environment and forms no part of the claimed design.