A person who can ruin a weekend, picnic, concert, sporting event, or any other kind of activity that you may have planned with your significant other by inviting themselves or guilting you into inviting them. These people are commonly refereed to as a Third Wheel. Third Wheeling is not cool and is frowned upon.
Dude! She's such a Third Wheel, I cant believe she tried to go to prom with them.
68👍 112👎