very stupid► crazy not at all sensible or reasonable, especially in an annoying or shocking way : · I said I enjoyed doing exams, and she looked at me as if I was crazy!· Ian's got some crazy plan to drive all the way across Africa.· The farmers can make more money by not planting crops - it's crazy, isn't it?· You're crazy to think of hitch-hiking on your own.
► ridiculous/absurd something that is ridiculous or absurd is so stupid that you can hardly believe that it has been done, said etc: · I've never heard anything so ridiculous! Of course I haven't been trying to avoid you!· an absurd suggestion· This is ridiculous. You've only known him three days, and you're going on holiday with him!· It's absurd to think Porter flew into a murderous rage just because he had an argument with his girlfriend.patently ridiculous/absurd (=used to emphasize that something is very ridiculous indeed): · This patently absurd argument is often used by anti-gay groups.
► ludicrous completely unreasonable or unsuitable: · The telephone lines are only open during office hours, which is ludicrous in this day and age.· She wears short skirts and dyes her hair pink, which looks ludicrous on a woman her age.
► laughable so stupid and unbelievable that it makes you want to laugh: · The government's attempt to privatize the prison service has been simply laughable.· It would be laughable if it wasn't so serious.
► idiotic very stupid and likely to involve unnecessary risks and dangers: · Wyatt was nearly killed as a result of that idiotic stunt.· If that wasn't idiotic enough, the company went on to sack fifty percent of its skilled workers, replacing them with untrained apprentices.
► hare-brained: hare-brained scheme/plan etc a plan that is very stupid and cannot possibly be successful: · Alice had to figure out how to pay the rent after Ralph spent the money on another of his hare-brained schemes.
► inane: inane remark/comment/conversation etc stupid and completely meaningless: · Penny began an inane conversation about the book she was reading to fill the silence.· Bad acting, weak script and inane dialogue -- this movie is truly awful.
very stupid or without much meaning: 
Most pop lyrics are pretty inane.