my dip stick flops around loosely in the hole (going to get hassles on this

The outcome of this is that I was beginning to believe that the big end bearings were starting to go, but because it comes and goes it took a bit of working out what was happening, never heard of a crank fixing itself before lol.
it is worse round right hand corners, and when I wiggle the dipstick with the motor running it tried to launch the dipstick into the atmosphere, which nearly had me reaching for some clean undies lol.
the top of the dipstick has a rubber plug round it but its still not enough to stop it flopping around.
anyone else had this problem, and how did you sort it???