A friend has a hair follicle drug test. he took 2 hits of pot 2 and a half weeks agoand hasn't did it for 3 months previous to this. will this show up?

Maybe.: Marijuana stays in the blood stream for up to 30 days. A hair test may detect as much as 3 months ago.

Likely yes: If the test is performed correctly and the hair is cut at the scalp. A hair test cannot detect recent drug use - ie less than 5 days before the test. They are to test for long term exposure. Blood tests should be used to test for recent marajuana use.