What does nemo me impune lacessit mean?

"No one provokes me with impunity."

http://24carat.co.uk/nemomeimpunelacessitframe.html

"No one attacks me with impunity."

-motto of Scotland and of the Order of the Thistle

http://www.m-w.com/dictionary/nemo%20me%20impune%20lacessit

(This page also provides an audio recording of the phrase.)

NOTE: "impunity" means "without punishment" or "exemption from punishment, penalty, or harm".