flat tire

Short definition from Wiktionary

Noun

1. 1
   A tyre of a motor vehicle that is deflated, especially one deflated because of a puncture when in use.
2. 2
   The result of stepping on the back of another individual's shoe in an accidental act, or deliberately to bully or tease this person, so as to cause the back of the shoe to collapse under the heel.
3. 3
   A bore; a person who is no fun.