thirdsday

Third Wheel

One who deters the socialization of a couple, perhaps when being invited out of pity or through a feeling of duty. This person may be eased into the situation by being allowed to stay in an envirnment he or she has become accustomed to (perhaps a kitchen, where the third wheel can bake cookies for the couple.) The third wheel may feel uncomfortable about watching the couple canoodle on his or her sofa, but none of this is taken into consideration.

Not to be confused with a tricycle.