This is Nick's tattoo:
The tattoo is a Dostoevsky quote, written in a letter explaining his mock execution in 1849. The full quote is as follows:
"They made us put on the white shirts worn by persons condemned to death. Thereupon we were bound in threes to stakes, to suffer execution. Being the third in the row, I concluded I had only a few minutes of life before me. I thought of you and your dear ones and I contrived to kiss [my friends] who were next to me, and to bid them farewell. Suddenly the troops beat a tattoo, we were unbound, brought back upon the scaffold, and informed that his Majesty had spared our lives."
The quote is just above my right elbow in fairly small, bookish sized font.