Bullshit refers to (usually male) bovine feces. Also used as a colloquial epithet for unsubstantiated drivel.
Bullshit in popular culture
Penn & Teller have a television program called Bullshit!, in which they serve as self-anointed debunkers of whatever pisses them off.
Bullshit in politics
Most of it.
Bullshit in religion
All of it.
Bullshit in the garden
This is the one truly useful location for bullshit. After a suitable period of composting, it makes great fertilizer and an excellent soil conditioner. Certain plant species are adapted to thrive in it, such as the turdblossom.
In the Turd World, bullshit is used as a source of free energy.