Mine was when I was playing in my sandbox at about 8. I was building a sand castle. Then all of a sudden my cat Whiskers jumped out of the second story window into the sandbox and broke both his legs.
My beloved Whiskers emoted in fits of pain. In fact, after that incident we changed his name to Whimpers. I don't think he liked the name Whimpers, but we called him that until his dying days. He just suffered a couple broken legs is all. No biggie.
I wonder if he jumped out that window because he so badly wanted to be with me in the sandbox. That's what I'd like to think.
Anyways, R.I.P. Whimpers.
"I'd trade these Rox for a Box of Rox" - Me on My Wedding Day