if there is a fifty-fifty chance of something happening, it is equally likely to happen or not to happen.

I'd say he's got a fifty-fifty chance of winning the race. (usually + of + doing something)

• have designs on
• have designs on someone
• have designs on something
• have dibs on
• have dibs on something
• have done more something than has had hot dinners
• have done more something than someone has had hot dinners
• have done more than has had hot dinners
• have done more than someone has had hot dinners
• have [done/seen/had etc.] more something than has had hot dinners
• have [done/seen/had etc.] more something than someone has had hot dinners
• have [done/seen/had etc.] more than has had hot dinners
• have [done/seen/had etc.] more than someone has had hot dinners
• have down on like a ton of bricks
• have down on you like a ton of bricks
• have down pat
• have down to a fine art
• have down to a science
• have ducks in a row
• have ear
• have ear to the ground
• have egg on face
• have egg on your face
• have end away
• have eye on