A Lewis dies from a mate's pod when the team spawns.
A Lewis takes the Trident or Stalwart.
A Lewis shoots his teammates in the back with his Trident.
A Lewis walks on mines.
A Lewis is shot by his own turret.
A Lewis runs under the wheels of vehicles.
A Lewis likes to take a hot bath in lava.
A Lewis dies running under the Tesla Tower.
A Lewis runs under the Tesla Tower to get his stuff. (infinite cycle)
A Lewis throws strikes too close of the defense objectives.
A Lewis shots Warlords with ineffective guns.
A Lewis runs a marathon before reanimate.
A Lewis crosses a continent for a single sample.
A Lewis kills every little bugz in the screen. (Spread managed democracy!)
A Lewis walks over his mates with his mech.
A Lewis don't carry ammo and ask for it in game.
A Lewis doesn't wait for his mates to get on the shuttle.

Community additions :

A Lewis throws mine fields without warning his fellow Helldivers they are there.
A Lewis will stand in place as he fires or reloads, refusing to strafe or take cover as High Armor enemies close in on him.
A Lewis repeatedly messes up his stratagem codes. (they never skip legs day)
A Lewis brings "useful" mech and let you do all the work.

I made this guide as a joke, Lewis can sometimes be tiring but they are essential to the survival of old coop games. Be kind with them. We were all Lewis.

There are probably things missing, tell me I will add it.