Burn Notice2007

Michael Westen:
[narrative] It may surprise anyone who has left on a stove burner, but natural gas is odorless. The smell most people think of as gas is actually an additive called T.H.T.

[highlight of those initials on a bottle of "Tetrahydrothiophene"]

Michael Westen:
which means making people think there's a gas leak is as simple as pumping T.H.T. in the air with a portable pump and some rubber hose. It's safe, effective, and easy to deploy, but it smells like you've just wandered into an open sewer. Then you just have to get the package in place without anyone getting suspicious.