packed in like sardines
Extremely crowded, as in I could barely breathe—we were packed in like sardines. This term, alluding to how tightly sardines are packed in cans, has been applied to human crowding since the late 1800s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.