impulse buying 
noun [mass noun]
The buying of goods without planning to do so in advance, as a result of a sudden whim or impulse.Is that something like impulse buying at the supermarket?...
- Big savings can be made by curtailing impulse buying and tracking every expense and interest rate charge, creating a budget plan and sticking to it.
- When sales shopping, Sally advises against impulse buying - that's how mistakes are made.
Derivatives
impulse buy
- Get more for less by learning to control your ' impulse buying '.
- At the shops earlier I suffered an impulse buy.
- In the, impulse areas near the register, where grocery stores put chewing gum, place items for gun-related impulse buys.