I was flipping through some of my childhood comics and was shocked to see a rectangle cut out of a page in Avengers #155!
I then realized I had used a coupon on the opposite side. I grew up in Rural Arkansas, so if I wanted any comics-related material, I had to mail off for it. Occasionally, cut my precious comics. I must have ordered Bring on the Bad Guys from this one.
I then noticed I had used a pen and colored pencils to draw on the page across from it.
I have absolutely no memory of doing this, but I know I always hated to lose any comic story to coupons. Voila.