The ornamental design for a men's briefs, as shown and described.
FIG. 1 is a front elevation view of the men's briefs of the present design, shown in a state whereby the fastener strips are engaged;
FIG. 2 is an interior plan view of the men's briefs of FIG. 1 laid flat.
FIG. 3 is an exterior plan view of the men's briefs of FIG. 1 laid flat;
FIG. 4 is a side elevation view of the men's briefs of FIG. 1;
FIG. 5 is an opposite side elevation view of the men's briefs of FIG. 1, shown in a state whereby the fastener strips are not engaged; and,
FIG. 6 is an enlarged detail view of the tab section located on the men's briefs of FIGS. 1-5. The broken lines are boundaries of the detail and form no part of the claimed design.