It's called PMS because of random nature of it (with always deadly end results) - just like in real life
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I have another proposition - complete weapon list!
1. Duke Mighty Boot - in normal mode Duke kicks like a mule and in alternative fire he kick aliens directly in the nads which stuns them for few seconds (good for stronger aliens), on steroids he deals "Nuke-Kicks" which are so fast and so powerful that the energy released on contact with the atmosphere or any solid matter is comparable to small atomic charge
2. Golden Eagle Gun - more like balls-of-steel casull .454 full-auto fire (like those pimped glocks) with dum-dum ammunition (recommended for aliens by the Geneva Convention) than wimpy desert eagle .44 - this config propably would rip off normal guy hand but Duke is immune to bland normality
3. Universal Railgun - gun that serves as shotgun, ripper and rpg - it has mini-fusion chamber instead of rounds with 60 pellets inside, fusion chamber is the power source for the rails which can shoot 15 pellets at once, 12 pellets per second or shoot the fusion chamber itself creating thus a mini-rocket (that is like a anti-personel mine when explodes with all those 60x0.177)
4. Pipebombs - just pipeboms, classically remote detonated, timer-fused, proximity-fused (like in Blood) and special with fusion charge (that kills even thru walls by gamma radiation making aliens glow shortly first like on x-ray) and psycho gas (aliens dance and act like retards for 30 seconds - easy to kill but difficult to hit when they jump all around the place)
5. IO gun (inside-out gun) - creates bizzaro blackholes inside alien bowels which blows them inside out and killing them from blood loss and organ rupture - doesn't work on stronger more massive enemies
6. PMS gun - maybe with switchable fire mode? this way it should be called STFU gun (shrink-to-freeze-up gun)
7. Pete Burns Gun - changes aliens into their sexy (not always) human female counterparts, Duke can perform shake-it-baby on the to regain lost ego
8. Chicken Nuggets box-of-doom - it is a throwable weapon, its delicious scent of fried chicken with 666 spices and herbs lure aliens into its proximity, but when some alien opens the box it reveals its true nature - the box is cursed and everyone who opens it is consumed by it and changed in a chicken nugget, Duke can pick up cursed box after and eat nuggets thus regaining health - he is immune to the curse because even ancient magical fast-food boxes know not to mess up with Duke
9. Mini-Duke - a deadly small 9inch Duke Nukem robot, he can be controlled directly or programmed to hold position, follow and attack - he is armed with mini-pipeboms and mini-ripper plus mini-nuke for remote detonation
0. BoomBox with Bieber record - most powerful weapon in the galaxy, aliens will try to kill themselves while hearing this music (jump through windows or into pits, run into walls banging heads, strangle themselves or simply shot in the head) or slowly die from brain damage if unable to commit suicide any other way - Duke himself is immune because he listens to Megadeath all the time, alien bosses are also immune because they created Bieber in the first place