make a pig's ear of
make a pig's ear of (something)
To do a very poor job of something; to ruin something completely. Primarily heard in UK. I'm going to need to start this table over again from scratch—I really made a pig's ear of it. Janet made a pig's ear of the Jefferson account, so I'm going to need you to come in at the weekend and put things in order.
make a pig's ear ofbungle; make a mess of. British informal
This probably developed with humorous reference to the phrase make a silk purse out of a sow's ear (see silk).