Back in the fall of 1990, when Nirvana only had one album to their credit and were only beginning to make a name for themselves on the Washington state music scene, Kurt Cobain was dating a woman named Tobi Vail.  She was the drummer for one of the original "riot grrrl" bands, Bikini Kill. They were a loud and vigorous punk rock group that could work up quite a sweat with their agenda to reshape the world.

One night after getting together to paint the outside of a pro-life pregnancy clinic with protest messages, Kurt and Bikini Kill's lead singer and songwriter, Kathleen Hanna, were hanging out in his motel room, talking about things like anarchy, punk rock, and politics. Once Kurt had fallen asleep, Kathleen took a Sharpie and playfully scrawled a message on his wall: KURT SMELLS LIKE TEEN SPIRIT.

At the time, he took it to be a visionary statement. So powerful, in fact, that it inspired the lyrics to a song that he would eventually create and include on Nirvana's next album, Nevermind.
It was only later that he learned that Kathleen was merely commenting on how the aroma of her bandmate Tobi's favorite deodorant, a Mennen brand called Teen Spirit, left a detectable trace on Kurt.