One railbird mocked my selection of Animal Kingdom and offered to book my bet.
From the suntimes.com
Besides, what railbird wants to bother with a race that covers only 350 to 550 yds.
From the time.com
Presidents of the participating universities look at the tournament as if they were one part railbird, one part alum, one part cynic.
From the nytimes.com
Dunn is terrific as the corpulent self-appointed leader of the railbird quartet, zipping around in his motorized wheelchair and sucking oxygen regularly through a plastic inhaler.
From the timesunion.com
More examples
A fan of racing who watches races from the outer rail of the track
The following is a glossary of poker terms used in the card game of poker. Besides the terms listed here, there are thousands of common and uncommon poker slang terms. ...
A rail or similar bird; A gambler; originally specifically a horseracing enthusiast
(Railbirds) spectators or lookie-lous watching the action.
Someone who hangs around a poker room who watches the games and/or is looking to get into action.
A non-participatory spectator of a poker game
A person standing on the rail watching a poker game. Normally this is an ex-player who is now broke.
Person watching a game in a poker room and/or waiting to start playing.
Someone who watches poker games without playing in them.