I think by "bad", people are assuming this means shows that were critically panned and/or commercial flops.
Within these parameters, I must admit to love Mamma Mia! (which satisfies the former but not the latter). The cast recording is awful though.
"It's not always about you!!!" (But if you think I'm referring to you anyway, then I probably am.)
"Good luck returning my ass!" - Wilhemina Slater
"This is my breakfast, lunch and f***ing dinner right here. I'm not even f***in' joking." - Colin Farrell