It's a flag that has travelled the World to Republic of Ireland matches, but it may be missing from the Aviva Stadium this weekend for the World Cup qualifier against Austria.
Keogh suffered a health scare after Ireland's win over Uruguay last weekend, and he feels the flag went missing in the hours after the game before he ended up in St. James's Hospital.
"After the [Uruguay] game I got a few pints", Keogh told Newstalk Breakfast. "I got a taxi back to the local, and took bad in it, in Kavanagh's on New Street. The lads got me an ambulance."
"Between getting back to the local, and being in the ambulance and the hospital, I don't know where I left the flag. I know a few lads in St. James's Hospital. They tried to track it down and it wasn't there. I think it's in the back of a taxi."
The Dubliner is getting a replacement flag made for the game, but he is still looking for the one his misplaced last weekend. If anyone finds if he has asked for it to be dropped into a Garda Station.
"I'm sure they'll track me down", he concluded.
Whatever happens, Keogh will be in his usual spot in the Aviva Stadium on Sunday, health permitting. He just hopes to have his flag back.