Please check the video below and see if you can endure watching it until the end.
I fully appreciate that this was hard to watch. Now, to continue this experiment, please have a look at the video below and let me know which one you prefer to watch.
The information provided in both videos is pretty much the same but I prefer watching the first video!
To get serious though, nobody would expect you to go out on a beach with shaving foam, but you would have that in your hotel room or can buy it at a nearby pharmacy. You also don't wan't to touch the affected body area without gloves!
To really 'rub it in'. have a look at one more video of the result of actual box jelly fish stings on June 20th, 2009, in Belitung Island, Indonesia.