deadhead
Deadhead (noun) means someone let into a theatre or concert for free, or paid to be there.
Etymology
From dead + head. Some senses are derived from theater jargon (originally spelled dead head) for audience members admitted without paying, which probably arose in analogy to dead weight or deadwood in reference to their lack of contribution to revenue or in reference to their unenthusiastic (dead) response to performances. Perhaps even from Latin caput mortuum, alchemy term for distillation residue. As Paul Quinion writes: Similarly, the term was applied to a dull or lazy person, one who contributes nothing to an enterprise, only in the early years of the twentieth century, well after the theatrical and transport senses had become well established.
