You're not gonna let the stag get off scot-free are ya? A stag do in Prague without a classic stitch-up would be bad form. Add a stag arrest to the party plan and you've got comedy gold. Include it as part of a big bar crawl or on the way to an activity, and keep the big man on his toes. We'll make all the arrangements before you fly over to the Czech Republic, he won't suspect a thing!
One minute he'll be enjoying his cava, the next he'll nobbled by the long arm of the law! The Prague 'police' will cuff him, bundle him in the back of the van and whisk him off to be interrogated while the rest of you look on in mock horror. Apart from the guy who's sneakily getting it all on camera of course! Once he's out of sight, crease up laughing and continue quaffing the cava until he's released.
Hopefully he'll see the funny side. If he gets a bit precious he'll soon perk up when a scorching Czech stripper arrives on the scene and the fun really begins!