1. cause someone to have to answer a difficult question or make a difficult decision
put someone on the spot by asking them a difficult question
When you ‘put someone on the spot’ you embarrass them by asking a difficult question or forcing them to answer in front of others with no warning or preparation. Putting someone 'on the spot' can also involve putting someone in a position where they are forced to make a difficult decision when they cannot avoid it. Being put 'on the spot' is unpleasant, people in the media often put celebrities or politicians 'on the spot' by asking difficult or uncomfortable questions during a live broadcast for example where the interviewee cant avoid answering. An 'on the spot' fine is one which is issued immediately or which must be paid to the authorities before you are permitted to leave a situation where you have broken the law.