what are most used messages when someone reach his webhosting limits? I mean his shared hosting overloading webhosting server..

Which error messages of hitting limits, overloading, banned for limit reaching messages you know?

MySQL Error: "Too many connections"
"Bandwidth Limit Exceeded"
421 Too many concurrent SMTP connections
"too many concurrent processes"
"Allowed memory size of * bytes exhausted (tried to allocate * bytes) in * on line *"