I've only had it jump on me one time. I had worked three 12 hour night shifts in a row, got off Monday morning and jumped on the boat at 8am. We fished til about 3pm and I had a red bull and about 7 miller lights. We went to dinner that night with friends and I couldn't even eat I was so sick, it just hit like a train. By the time we got home I was shivering and sweating and drinking as much Gatorade and water as I could stomach. After some good sleep It turned around.

That being said I've worked out in it my whole life, and 12 years of it wearing long sleeves and a Kevlar vest. I take it much more serious these days, but as a kid I don't ever remember flinching. even in the attics and crawlspaces working with my old man.