The ornamental design for an americanfootballlamp, as shown and described.
FIG. 1 is a top view of the American football lamp of the present invention;
FIG. 2 is a left side view of the American football lamp of the present invention;
FIG. 3 is a front view of the American football lamp of the present invention;
FIG. 4 is a right side of the American football lamp of the present invention;
FIG. 5 is a bottom view of the American football lamp of the present invention;
FIG. 6 is a back view of the American football lamp of the present invention. The broken lines show environmental structure and form no part of the claimed design. The dash-dot-dash lines show the bounds of the claimed design and form no part of the claimed design; and,
FIG. 7 is a front perspective view of the American football lamp of the present invention.