I'm building the Star Wars Dagobah Training Diorama that I bought for Christmas and I had two "ouch" moments so far. The first was the edge of a black 1x8 tile on the base poking me under the nail and the second was during the placement of the 200-something trans-green pieces for the swamp. I realized "dang, for a building toy suitable for young children Lego pieces can poke the crap out of your fingers!" and decided to make this post.
What are your most physically-painful Lego building moments? I'm gonna take a guess that just like me most of them involve being poked under the nail too.