Khaosan road is one of the busiest roads in Bangkok and is popular because of the cheap hotels, stores, and booze. It's popular for backpackers. I think I can compare it to Bangla road in Phuket except in Bangla there are more activities there than here.
I haven't been to Khaosan road during the day but upon researching it, there are lots of stores that are open selling some Thailand stuff. But at night, the road is closed to cars and so it becomes a road of PARTY.
Upon entering the road, you will find yourself literally surrounded by music. Each bar has their own music so they can be really loud and sometimes you don't even know where exactly the sound is coming from cos they're all mixed up lol.
There are tables outside which are more fun than being inside the bars cos you can see people walking by and you can dance together. :D It can get really packed at 10pm onwards, which is more fun than being confined in a small place.
They serve different cocktails here but serving in buckets is popular here. I was actually shocked to see a whole bucket for what I thought would be a small drink for me. I was like "how tf am I gonna be able to finish this???". In the end, 
Laughing gas is very popular here in Khaosan Road. They basically fill the ballon with nitrous oxide and when you inhale it, you will experience a euphoric feeling - which is why it's called laughing gas. Most tourists and party-goers use this and it's like 250 baht per 10 balloons I think.
I have tried it for the first time and I didn't like it. It gave me a really bad rush in my head, made me laugh a bit but I felt dizzy so I didn't wanna try it again. Well, of course, it should be illegal right? Laughing gas apparently isn't a laughing matter for the police. :P
There are also vendors who sell snacks that you could eat while drinking. One of it was this dried cuttlefish.
This was sweet dried fish that I ordered along with the dried cuttlefish.
He had to flatten it again before putting it on the fire.
It was a nice snack especially for those who love dried seafood but I can't stand it now anymore. Even just smelling it... cos I had a really bad hangover after this night to the point where
And of course, there are some fried exotic foods. :P
There are scorpions, crickets, cockroaches, tarantulas, worms, and small frogs... Of course they are safe to eat, but just it makes you think it's disgusting considering they're insects. :D
But then I was like "what's the point of going to Thailand if I'm not gonna try their exotic foods?" so I tried the scorpion for the lulz.
Tbh I was kinda brave since I drank a bit of alcohol so I was like not really caring, just curious on how it would taste like. I couldn't describe the taste exactly, but it was just like a fried something. It doesn't really taste anything and I have nothing to compare it with. Surprisingly, I finished them all even the butt and thankfully there wasn't any goo coming out of it else I would probably freak out. :P
I also tasted a fried cricket and it was more tasty than the scorpion I guess cos the lady put some pepper on it. :P
After the scorpion, it made my mouth itchy. Like the insides of it - tongue and back of my throat. I asked the lady and she said it's not supposed to itch. So my best guess was I'm having a mild allergic reaction (cos I think maybe cos I'm also allergic to shrimp and they're kinda same dunno lol) but thankfully I didn't have to drink antihistamines. I just drank water and after 30 minutes or so, it went away.
The tarantulas didn't look as tasty as scorpions because of their large butts. :P
Going to Khaosan road was a nice experience and I recommend you to visit when you're in Bangkok. There are some other vendors that sell foods like fruit shakes, rice porridge, kebabs, and other shits but I wasn't able to take photographs since we were there to party. XD