Start your bachelor party with a bang at Bangkok's famous nightlife scene. Make your way to Khao San Road, where you'll find countless bars, clubs, and restaurants. Enjoy a cold beer, sip on a cocktail, or take shots with your buddies. Make sure to try the local Thai beer, Chang, and the infamous bucket cocktails. Don't forget to visit the red-light district of Soi Cowboy, where you'll find a strip of neon-lit go-go bars and clubs.
Take a break from the city and head to Chiang Mai for some adventure. Start the day with elephant riding and bamboo rafting at the Maesa Elephant Camp. After lunch, visit the Chiang Mai Grand Canyon for cliff jumping and swimming. End the day with a visit to the Chiang Mai Night Bazaar, where you'll find unique souvenirs and handicrafts.
End your bachelor party with a legendary beach party at Koh Phangan. Take the ferry from Koh Samui and head to Haad Rin Beach, where the famous Full Moon Party takes place. Dance the night away on the beach with thousands of party-goers. Don't forget to paint your body with neon paint, wear your best beach attire, and try the local bucket cocktails.
If you have more time, consider visiting the islands of Koh Phi Phi and Phuket for more beach parties and water activities. To maximize your fun, hire a private tour guide who can customize your itinerary based on your preferences. Don't forget to try the local street food and visit the rooftop bars for amazing views of the city.