At last spring I brewed a batch of belgian ale that turned to be highly over carbonated. It comes out of bottle quite merrily, but so far none of the bottles have exploded or even leaked by themself.
Now to the tricky part, I have to move out of the place where the bottles are stored and I think it would bee too nasty joke to leave bottles behind.
So the question is how to safely transport over carbonated glass bottles via car?
If the beer is overcarbonated, I'd just degas it. Lift the cap of each bottle, let the CO2 escape until the foam reaches the cap, let go; repeat as many times as necessary, waiting for the foam to fall back between each degassing. It can take a couple dozen sessions over several days to reach the desirable/safe carbonation level.
If the beer is not cooled and you wish to retain the high carbonation, you can chill the beer and leave in the fridge for a longer while to let the CO2 properly dissolve. A day should be quite enough. Then, place the bottles in an ice box and transport them in it. The low temperature will keep the CO2 well dissolved and thus the pressure in the bottles will be significantly lowered.
I ended up transporting the bottles in a following set up: put bottles to a plastic bucket and filled the space beetween them with insides of an old pillow. I packed the buckets to car in a way they could not move.
It worked quite well, none of the bottles exploded but I also drived quite carefully.