Means literally 'do me a favour'. The lemon part is Cockney rhyming slang, and is short for 'lemon flavour', so in other words it's really "do me a lemon flavour"
The usage is mostly to reject an offer or behaviour of some kind, due to its being undesirable in some way (as opposed to actually asking for a specific favour).
The usage is mostly to reject an offer or behaviour of some kind, due to its being undesirable in some way (as opposed to actually asking for a specific favour).
by NoMoreSecrets December 6, 2007
Rare but recorded London phrase for 'Do me a favour'. Totally mystery origin, unless you know the answer.
by David from Kingsbury April 13, 2006