From Longman Dictionary of Contemporary Englishwallywal‧ly /ˈwɒli $ ˈwɑː-/ noun (plural wallies) [countable] British English informalSTUPID/NOT SENSIBLE someone who behaves in a silly way Stop being such a wally!
Examples from the Corpus
wally• I should have left you to look like a wally.• He was just another wally like anyone else.• Turned out that some well-meaning wally had given it a tankful of unleaded two-star.• One of them was a real wally, so the others didn't let him in on their plan.• You look like a right wally in that hat.• Look at those wallies jumping around and pulling faces behind the TV reporter. 