Barbarian player? OK. First things first. While he's unlikely to rip your arms off, I think it would be best to paraphrase Han Solo and "let the wild man win". Some more specific suggestions follow:
- 3.x is actually a pretty bad choice for a barbarian - the semi-literate generally struggle with games that run into hundreds of pages. I recommend making up his character for him and just telling him, "Your character strong! He take many skulls!" This is an excuse to annex the important role of the barbarian's lowly scribe, thus making a good case for your continued access to manual dexterity.
- If the ref considers the build to not be all that impressive and considers it wise to have the barbarian's character miss, fail saving throws, etc, refer him to the Han Solo rule, above.
- Do not, I repeat, DO NOT attempt to LARP.
- It's best if you play at someone's filthy apartment. Yeah, you'll always feel too nauseous for gaming pizza, but on the other hand, you won't have to apologize to the host's mother/wife/girlfriend for what the barbarian did to her furniture.
- Keep the barbarian away from mothers, wives, girlfriends - in fact, keep them away from women in general. Follow this rule even if the barbarian is a woman - unless your female relatives, significant others, and friends are fond of honor duels and friendly rough-housing that results in broken bones.
- If Jocks made your life hell in highschool, and they're still dicks, make sure to crash one of their parties with the barbarian in tow...