Yes, having Garfield and company wrapped clumsily around Christmas gifts has gotten you points for charm in the past. Unfortunately, the past was when you were twelve, and your poor excuses for gift wrap aren't quite going to cut it anymore. These days your fianc expects things either creatively cloistered in fancy bags or specially wrapped at the department store, but your boys don't care, right? You can give them their groomsmen gifts in any old way.
Stop right there. Look, just because you can get away with giving your friends things in plastic bags, or pulled "ta-da!" style from out behind your back (hey, at least it beats making them choose which hand the gift's contained in), it doesn't mean you should be that lazy, especially when it comes to giving something as important as groomsmen gifts. Even if you're not in it for style points, less-than-shoddy presentation at least shows that you thought about them beyond remembering how to spell their names for personalized groomsmen gifts.
All this doesn't mean you have to go Martha Stewart full throttle into hand-scrapbooked wrapping paper and scissor-curled ribbons, but at least do one better than grabbing last Sunday's funnies and getting newsprint all over the clumsily-placed Scotch tape. Take a look at a few of these tips for giving out presents that look as good on the outside as you know they are on the inside.
When in doubt, a cheap and entertaining option is novelty gift wrap. After all, nothing says, "I value your friendship," like gift wrap printed with strips of bacon or Super Mario Bros. This is best for the less serious groomsmen gifts - think golf ball cufflinks rather than an engraved picture frame containing a picture of your most meaningful moment as friends.
Boxes: gifts come prepackaged in them for a reason. Since it's not like you're giving hair dryers as groomsmen gifts, you can probably preserve some of the mystery of the gifts come in a nice box. This works the best with smaller groomsmen gifts, obviously, and it can make presentation tricky - if you're giving a guy something in a small jewelry-sized box (a nice pen, maybe), it's probably best to go for a friendly toss rather than pushing it across the table as you're out to dinner with your friends.
If your idea of wrapping involves rolling the paper around the gift and twisting the ends together like a piece of butterscotch candy, just bribe your fiancée with a nice dinner out and see if she'll wrap the gifts for you. Bemoan your big clumsy fingers and praise her delicate hands (important: don't imply they're well-suited to doing other menial work, this will backfire horribly) while giving her your best beseeching look. Explain how important it is to you that your groomsmen gifts look presentable, and she might be swayed by the charm of true manly friendship.
The above tip may fail; if it does, the likely outcome will be that she suggests you just get your groomsmen gifts professionally wrapped like you always get hers done. At some point you just have to bite the bullet, man - get it done. Just make sure they stick with a good solid color like navy or forest green, especially if it's around the holiday season. Groomsmen gifts are just not a good time for snowflakes or silver glittery accents.