A blonde, a brunette, and a red head are stranded on a sinking raft 1000 yards away from an island. They all decide to swim for it.
The red head jumps in, swims 200 yards, gets tired, swims another 50 yards, then drowns.
The brunette jumps in, swims 300 yards, gets tired, swims another hundred yards, then drowns.
The blonde jumps in, swims 950 yards, gets tired, then swims back to the raft...