Try charging a SAW, palm down. That'll wake you up in the morning.
See the ejection port cover under the charging handle? It latches closed, but as you pull the bolt rearward, it pops open. If you don't know the SAW, and you pull it back with your palm down, it'll lay open your thumb like a filletted fish.
No. Never done it myself. I had a boot try to argue with me on the proper way to pull the bolt back, so I just handed him my gun and said, "here, show me." Then I made him clean it after dropping it in the dirt.
For reference, you do it palm up, from under the charging handle. It gives you more leverage, control over your muzzle, and keeps your thumb from getting sliced open.