The last time I tried this it still worked but heres what you have to do6):
Step 1
First -> The player must have a small effect on them (maybe have them drink noggenfogger elixir)
Step 2
Second -> The player needs to be mounted.
Step 3
Third -> Get the player in the water.
Bam! Disconnection!
The player will continue to DC until the small effect wears off or a GM takes action.
you can have the elixir while on a mount if they have the effect that makes u smaller it will work.