Professor decides to go back for his rucksack. Stalker and Writer are worried he will get lost and die, but decide to press forward through the tunnel. They exit the tunnel and find Professor sitting on a rock, enjoying coffee and sandwiches.
The dry tunnel is not actually a dry tunnel.
Professor is a constant source of hilarious situation. But his most hilarious moment is when he's ranting at the stalker when they approach the Room... a phone near them starts ringing, professor denies the call and continues shouting at his now-totally-shocked companions. Only several seconds later he also realizes this phone is in the abandoned building several kilometers into the zone, with everything completely wiped out. Followed by his Crowning Moment Of Awesome, when he decides to make a call.
On the other hand, this can be very convenient if the NPC in the fire is someone who carries a unique weapon. Oh, you want Bes's silenced AK but don't want to cap him yourself? Come back in half an hour, he'll be medium rare over the fire pit in the scrapyard. You don't have to kill him...you just have to wait forhis friends to get hungry enough.
Occasionally, the AI will lose the squad-based tactics routines and you can wipe out entire squads by standing inside a building with a shotgun and killing them one at a time as they run in the door. Bodies can pile up just inside the doorway, and those remaining outside will immediately conclude that the best course of action is to run in like the last twenty guys did.
Similar hilarity will ensue if you find a couple of bandits or expendable Loners (if you're feeling cruel) inside a building and have a spare rifle grenade (or an RPG, if you're feeling extraordinarily wasteful). If you're very very lucky, not only will the men inside be killed (instead of relatively unharmed and pissed off at you) but one or two will be in hilarious positions, such as being partially glitched headfirst through a wall with his hindquarters hanging out.
Actually this can happen in any indoor area where explosives are involved. Running around in the CNPP at the end of Shadow of Chernobyl, you can kill three or four Monolith troops with a pair of grenades if the planets align properly. How? Kill one with the first grenade and possibly wound the others, then send the body and his gun flying at lethal speeds with the second blast. It's almost impossible to do intentionally, but if it does you've just managed to kill someone with a gun without firing it at them.
The PA announcements at the Freedom base in Clear Sky will occasionally be interrupted by arguments between the camp trader, Ashot, and the technician, Yar. Listen for yourselves.
To make this even funnier (in a way), you can prime a grenade, and will throw it as you teleport into the bunker. And it will blow up right after he says the line. What the hell indeed.
After the team you form in Call of Pripyat all makes it to Pripyat and finds out Degtyarev works for the military (which prompts Zulu to leave), all Strider has to say is "I don't give a rat's ass about who anyone works for."—in the same Creepy Monotone he says everything else in.
Hawaiian is just funny for being a living Mood Dissonance. In the middle of the Zone he's trying to create a jovial, tropical atmosphere in his store, yelling "Aloha" and insisting "it can be fun around here!".