Picture this: the harried ad executive, sitting in his cushy leather chair, is panicked.

Since guerrilla marketing has entered the mainstream, however, the term has been applied to just about any type of advertising that attracts attention in an unconventional manner.

If you'll indulge us, we'd like you to step into our time machine. It's 1987.

When some starry-eyed startup shocks the world with an underground marketing campaign that costs nothing but causes shockwaves for months, it's called guerrilla marketing.

Some guerrilla marketing is even done to support good causes though much of it is created to line the pockets of giant corporations.

Here are just some of the growing number of subversive advertising campaigns that have been to raise global awareness.

Urban camping means different things to different people, from living without a vehicle or electricity and plumbing to squatting in unused properties and more.

These street art images and biographies merely scratch the surface and begin to convey their amazing artistic talents though sample artworks and street chalk drawings.

Here are some engaging types and works of visual and performance art that have prompted critical thought or stirred up controversy, all without getting the artist(s) in trouble.

Subvertisements are an excellent means of turning the commercial world around you upside down, make humorous or critical commentaries on consumer society, or even get rid of ads altogether.

This group has managed to turn a street art hobby into a guerilla marketing campaign strategy.

Amazing but non-commercial forms of urban street art, from silly and creative projects to works both sublime and socially relevant.

We've combed the web to find the best of the best urban guerilla marketing campaigns on the ground, in the streets and in the air.