When you witness something groundbreaking when you are stoned.
California was milestoned when Proposition 19 passed.
by Mr. Cannabis November 01, 2010
When you smoke pot on a day that is a milestone in your life such as a 20th birthday.
(While High) Dude, your 20 on Dec. 10 in the year 2010..milestoneddd
by eschh December 10, 2010