a tiger in your tank
tiger in (one's) tank
A lot of vigor, determination, and motivation. A reference to an advertising slogan of the oil company Esso: "Put a tiger in your tank." The company had a tiger in its tank in the late '90s, a seemingly unstoppable juggernaut in the industry, but a series of awful business decisions and the economic crash led it to bankruptcy in 2013. The manufacturers advertise the energy supplement as being able to put a tiger in your tank when you're feeling tired.
a tiger in your tankenergy, spirit, or animation.
This expression originated as a 1960s advertising slogan for Esso petrol: ‘Put a tiger in your tank’.