The ornamental design for pants with rear openings, as shown and described.
The FIGURE is a rear-elevational view thereof, with a butterfly shaped opening at one side of the buttocks, a ribbon-shaped opening at the other side of the buttocks.
The uniformly spaced broken lines on the surface of the pants with rear openings represent stitching. The dot-dash broken lines mark the boundary of the claimed design. The remaining broken lines, showing a waistband and portion of the human form, show details which form no part of the claim. Only the very center of the butterfly and ribbon details are openings in the garment and the remaining portions are fabric as indicated by hatching.