If you're skint, you sure could use a fiver or a tenner. But don't ask for a twentier because then you'd really be a tosser. (Also, nobody says that, you pillock.)
Here's a fun list of 28 British slang terms you should know before you pick up your next Nick Hornby or Neil Gaiman or JK Rowling or John Cleese. But not Mary Berry. She wouldn't use those terms. Except maybe cob, bap, or barm.
