My girlfriend (now-ex, although not because of this) and I visited Egypt a couple of years back, and despite being fully aware of the danger of explosive diarrhoea, it was unavoidable.
I can relate to that.
I went there a few years back and me and the rest of the family suffered the same fate.
After a night of unspeckable unpleaseantness, we pop down to the chemist to get something to settle our tums before hitting the beach.
So we get down to the beach and break out these damn HORSE pills, I've never been good with swallowing pills and these blighters were pretty big! But sod it I was tired, I lay back on my sunbed and make an attempt to swallow them.
I promptly semi-choke and throw up on myself. No biggie, I get up, covered in vomit and walk down the beach to the nearest shower.
I get to my bed, finally manage to swallow the pills and try to relax, but my bowels had other plans, beacause, without so much as an announcement they decided to move on their own accord.
I get up and inform the family I'm going back to the hotel room, they ask where the hell I'm going, but I'm too busy, gathering up my stuff and what remained of my pride.
I think they understood what happened, but they had to remind me I had a scuba diving lesson later on that day...
So I went back to the hotel room, cleaned myself up and spent a good hour or so praying to what ever god that would listen that my guts wouldn't play up anymore. Or trying to figure out how the hell I was going to explain the mess in my wetsuit to the instructor.
Thankfully though, the wetsuit remained clean.