Английский словарь американских идиом - let it rip

{v. phr.}, {used imperatively}, {slang} Don't be concerned; pay no attention to what happens. * /Why get involved? Forget about it and let it rip./ 2. (Imperatively) Do become involved and make the most of it; get in there and really try to win. * /Come on man, give it all you've got and let it rip!/