Don't Tread on Me is an alternative English translation to the Latin phrase, noli me tangere (which is more literally translated to "Touch Me Not," which is supposedly what Jesus said to Mary after she was all like, "Hey, you're my son, aren't you?" after His resurrection and he was all like, "Shhh, no -- be quiet about that," but whatever) and is also the slogan used on the Gadsden flag from the American Revolution.
Designed by Christopher Gadsden in 1775, the flag is a yellow banner charged with a coiled rattlesnake facing towards the hoist, the words "DONT TREAD ON ME" positioned below the snake.
There isn't an apostrophe in the word "dont" which is typical of the era. Children of the American Revolution were rarely schooled past the third grade before being sent off to the fields to catch and train lowland streaked tenrecs to detect blankets tainted with the plague in support of the war effort. Nowadays, there's really no excuse for not knowing when to appropriately use an apostrophe -- just ignorance, I guess.
Anyway, this quilted fleece jacket in no way resembles the Gadsden flag, aside from the fact that we're calling it Tread. But it's warm AF, so there's that.