When one is experiencing extremely high levels of various emotions that may agitate another person in their company and really needs to just chill out or relax, the annoyed party in their presence can tell them to take a chillaxative, therefore rendering it appropriate for that person to fully let go and purge their stresses until they reach a serene state of calmness.
Metaphorically speaking, a "drug" a person will tell another to take when their level of stress or aggression reaches profound heights in which it is now useless to merely tell them to "chillax".
"It's no big deal, dude... You're girl came onto me, but I didn't put itall the way in, so just take a chillaxative!"
cool as shit. axative can be added to many words if they sound right, such as for computer chat geeks who can now use lolaxative which means "funny as shit".