1. An old cheap car.
2. A tank-top like undershirt that has vertical stripes.
3. Short for "beat her".
1. I drive an old beater.
2. My beater is so comfortable, I could wear it all the time.
3. I'm so mad I think I'm going to take off my shirt and beater. (this is a double pun because if the guy is wearing a beater under his shirt then he is in the act of beatingwearing a wife beater
and he is also going to "beat her".)