'Not a dry seat in the house' is an old cabaret-artist phrase, which can signify achieving taking the audience to extreme emotion of either sorrow or joy - or indeed hysterical laughter. The interesting aspect of the country music suggested by Spaw is that all these different effects can be seen on different people in the same audience!

Taking the physical aspect of this discussion to a whole new low, I'm told that after the Beatles concerts of the mid-60s, the theatre aisles were literally awash.

-IanB