I was on the Mini-Baja team in college. We got a couple of new 8HP engines from Briggs. "Let's put one on the dyno!" We unbox it, place it on the dyno, hook it up, gas it up, and get it started. It started up right away and idled perfectly, after all, it was brand new. We let it warm up a bit, then rev it up and apply the load. All is going well, and then it starts slowing down. We check for full throttle and then back off the load a bit, but it's still slowing down, and then it stops. Yeah, no oil.
Did the timing belt on my '96 Ranger. Could not get it to fire. Checked the plug wires about 10x. Gave up for the day. Got up the next morning and realized that I was doing both coilpacks the same. Swapped the back (or front, it doesn't matter) per the diagram and it fired right up.
^did the no-oil trick once at the kart track. First time at the races by myself (dad had to work). First engine failed in break-in (dad built that one, timing key broke). Tossed the spare on. Made it half a lap thinking "man, this thing has some power today! Wait, did I put oil in this thing?" and it promptly seized up. Packed up and headed home.