It is 1963. Ernest Tilley (Danny DeVito) and Bill "BB" Babowsky (Richard Dreyfuss) are door-to-door aluminum siding salesmen in Baltimore, Maryland. Working for different companies, the "tin men" are prepared to do almost anythingâlegal or illegalâto close a sale.
Their first meeting is when BB buys a new Cadillac and almost immediately crashes into another Cadillac driven by Tilley. The accident is caused by BB, as he reverses into the street from the dealer's forecourt. Tilley, though distracted, clearly has the right of way. Each vows to get even.
After they smash glass on each other's cars, BB takes it a step further. He sets out to seduce Tilley's wife Nora (Barbara Hershey) as an act of revenge. When he calls Tilley immediately after having sex with her, Tilley tells BB to keep Nora; he wants to be rid of her.
Exhausted by their rivalry, the two men decide to play a game of pool to decide who should get her. BB loses, but he does not honor the bet. He has fallen in love for the first time.
A newly formed Maryland Home Improvement Commission charged with uprooting corrupt sales practices in the home-improvement industry subpoenas both men and takes away their licenses. Reconciled to their fate, Tilley and BB begin sharing ideas for a new business.

Question: What did BB and Tilley do to each other's cars?
Answer: smash glass
Alternative answer: break the glass