For me jalapenos are relatively mild as far as heat/spice goes, they have some warmth to 'em no doubt but they're what I consider to be mild. I've built up a tolerance to spice/heat over the years, not a huge tolerance like some spice/hot heads but certainly far more so than the average person (I also straight up enjoy a good burn).
Years ago, back around 2010, at a little kick-back party/chill sesh with the boys my buddy had a bag of dried ghost peppers that someone gifted him...We were all having some beers or whiskey to drink that night and I was trying to get someone else to take a bite of one with me lol. My friend David (RIP) said he was down, so we each grabbed a pepper and took a bite, about 1/3 to 1/2 of the pepper each. The thing was I already knew what I was getting into lol, I had previously taken bites/nibbles of the ghost peppers several times before because I love a good burn sesh/rush, and David had never had anything anywhere near that spicy/hot before lol...
...I felt so bad, it absolutely wrecked & tore David up...Dude looked like a mess, eyes watering/tears pouring down, snotty runny nose, face super red/flushed, moaning & grumbling in pain, about 5 to 10 min after eating it he was in the bathroom puking his guts out (he was also drinking whiskey that night while I was drinking beer, so I can only imagine what a tummy full of alcohol and ghost pepper would be like lol). About an hour or two later he was feeling better but it definitely fucked up his entire night.
Yea ghost peppers are no joke!...Ghost peppers are where I draw the line as far as taking a direct bite of the pepper lol. There are now several other peppers that are considerably hotter, 2 to 3 times more scovilles than ghost peppers. Ghost peppers lost the title of "hottest pepper in the world" some years ago, there's a handful of new strains/varieties that are substantially hotter/richer in capsaicin than ghost peppers!
Ghost Peppers rank around 800,000 to 1,000,000 scovilles
Trinidad Scorpion Peppers rank around 1.2 to 2 million scovilles
Carolina Reaper peppers, 1.4 to 2.2 million scovilles
Pepper-X, 3.1 million scovilles!!
For comparison to milder/more common "hot peppers", Jalapenos have around 2,000 to 8,000 scovilles and Habaneros around 100,000 to 300,000 scovilles.
Often times things that are said to be "spicy" don't even tingle my tongue lol. My go to mild-sauce is habanero based and that has some warmth to it but def isn't what I consider to be hot, and the last few weeks I've been using a naga-jalokia (closely related to ghost pepper) based hot sauce which has a nice level of heat with out being too intense to enjoy the flavor.
I'm one of those dudes that puts hot-sauce on almost every meal I have at home lol, I love heat and the taste of spice/peppers. I've built of some tolerance to heat/spice over the years, but not on the level as some chili-heads are, eating a raw habanero will def give me a good intense (tho tolerable) burn where some chili-heads with high tolerance can eat a ghost pepper with out a flinch.
And one last ramble....A few of the times I've ate ghost peppers I've experienced a peculiar pain inside my ears, like internally where the ear-drum is, it is an intense/sharp/throbbing pain. The times I've had that ear-pain going on it overpowers the burning sort of pain I feel inside my mouth/throat...It is such a strange sensation/pain that I've never experienced before besides a few of the times I've ate ghost peppers, if that pain wasn't present I'd be more tempted to take a bite of one of the new peppers hotter that are hotter than ghost peppers.
...and super hots like ghost peppers, even a real strong/hot habanero sometimes, will absolutely give me an endorphin & adrenaline rush/high/buzz...I def feel a bit high/altered when eating something super hot/spicy.