Here's how to get those coupons out of magazines without destroying either, if you don't have a scissors or a ball-point pen.
Step 1: Magazine or Junk Mail Flyer.
Step 2: Fold the Coupon in Half, With a Strong Crease at the "cut" Line.
Step 3: While Doubled, Tear Down Along the Cut Line. Repeat on Other Side.
Step 4: Turn and Do the Same for the Top and Bottom.
(I could have been neater with this tear.)