(I used Mirelurk bait grenade because it causes 0 damage to the NPC. If you play the console versions, I suppose you can use bio-gas cannisters and cryo grenade/mines too but I think those cause a LITTLE damage, like 1 point).

1) Just summon up some Mirelurk Bait Grenades with the in-game console, its base ID is- 00030664

2) Reverse-pickpocket one into an NPC (it'll go live, but will do no damage and makes no one hostile)

3) Without exiting the give/take menu, give him more grenades. Those won't go live.

Not sure what the purpose for this is, unless you're trying to arm the Caravan Guards or something with Grenades...

Nice you answered it yourself.

Heh, I'd go for a nice rocket launcher or minigun if I ever wanted to arm those caravan guards- that's why it confused me at first. Of course, caravan guards with Nuka-Grenades...

I like arming the Big Towners, myself. Then watching as they turn the arriving mutants into Super Mutant Gumbo. It does my heart good to see those hapless twerps finally able to take care of themselves.

Nice.

Problem with giving them nuka-grenades is that they don't seem to take the increased blast radius of the nuka-nades into consideration when they throw, so I stuck with plasma grenades. Could be wrong, though.