1-does not understand joke due to cultural differences. Wants it explained in detail. Will nod and smile generously when it's all over.
2-does not realize joke is joke, takes it literally. May, therefore, take action, like asking for wherabouts of man from Natucket or organizing hirelings to seek out Interrupting Cow.
3-kinda amused but is competitive jackass, tries to tell funnier joke (DM, you're on!), probably fails. Is now bitter.
4-as 3 but NPC is so pretentious/ignorant that joke fails to register as joke with anyone who has Wis above 5.
5-offended that the PC is taking situations so lightly, roll initiative.
6-finds PC's sense of humor strangely attractive.
7-laughter triggers an ancient curse. NPC has been trying not to laugh since 799AD. Demon manifests itself through NPC's body.
8-laughs, buys PC a drink.
9-laughs, buys self a drink.
10-laughs, is already drunk, buys drink a drink.
11-thinks joke is so funny that NPC agrees to pretty much whatever.
12-laughs laughs laughs, then cries. Investigation reveals joke reminds NPC of traumatic parental situation.
13-laughs laugh laughs, then says "Oh, thank Or-Hossk! I needed that. It's been so long since I had a good laugh"--reveals secret mystery difficulty plaguing peeps hereabouts.
14-vomits with laughter. 1-3 embarassed 4-6 crazy viking type who just does that.
15-laughs, claps PC on back with unexpected strength. d4 minus 1 damage.
16-laughs, introduces PC to younger family member of opposite sex.
17-puritanical local value system. Accuses PC of being witch.
18-laughs, laughs, laughs hysterically, orders first available pie & begins smearing it all over body.
19-laughs, goes around to other nearby characters and begins saying "This guy! Oh, jeezus, this guy," and continually insists PC repeat joke to all of NPC's friends.
20-offers PC contract as personal entertainer. Pays 8 gp per laugh.
Once a result has been used, cross it out and write your own.