Used to be a slogan for DuPont (a chemical company), but now it refers to the practice of taking medication and/or drugs to make your life more enjoyable.
Becky: "Wow, Jenny was always so depressed, but now she takes a bottle of Prozac in the morning and washes it down with vodka, she seems really relaxed and happy."
Hank: "Oh, so she's discovered better living through chemistry!"

or

Slut: "Wow, your schlong is so hard!"
Old guy: "Yeah, I used to be impotent, but now I take Viagra. It's better living through chemistry..."
by jdawgzzz January 24, 2010
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