As an actual woman in tech, I'd say spend a couple days at the beginning figuring out what she's okay with, rather than treating her as a No-Fun Zone waiting to happen. Women, surprisingly enough, are individuals; there's no telling how exactly she'll fit into the team, which kinds of off-color humor are off-limits, and which ones she'll happily partake in. Just make it clear, both to her and to the guys who already work there, that she has the right to go "whoa, guys, too far" and be taken seriously--actually taken seriously, not just a perfunctory "yes ma'am" and an unrepentant repeat of the same crap five minutes later. Old habits die hard, but the problem is not an occasional ribald remark slipping out and followed by "whoops, should we tone it down?" A really crappy, hostile situation is one where none of the guys will voluntarily self-correct or tell another guy to back off, where the girl has to say over and over again that she doesn't want to hear any more goddamn rape jokes and come off like a nagging shrew over something that should be common courtesy, and where everyone (or even just That One Asshole who nobody ever says anything to) is deliberately pushing against the limit of what she'll put up with. Having an innuendo jar or a silly tie could help prevent that, or it could just make things more miserable, depending on whether her coworkers have her back or not.
(For the record, there is only one appropriate response to "please don't tell rape jokes in front of me," and that response is "okay." This has nothing to do with whether rape jokes can ever be funny and everything to do with not being a total asshole to the person in question. Yeah, I've had to explain this in real life, though fortunately never at work.)
This is assuming, of course, that by "remarks, double entendres and innuendos" you mean banter on the level of "that's what she said" and yo-mamma jokes. If you're worried about creepy personal comments, sexual advances, or stuff that's openly derogatory to women in general, that's not a "put $5 in the swear jar" situation, that's shit that needs to stop yesterday--not to humor an uptight female, but out of basic decency. If you wouldn't want a gay guy saying it to you, why the hell would you inflict it on a colleague who's probably had to deal with a lot more of that kind of bullshit than you have?
But beyond sexist comments and blatantly disgusting behavior targeted at her just because she's got tits, it really is a matter of comfort zone. Personally, I'd laugh myself into a hernia if I found out my coworkers had been walking on eggshells to avoid innuendos around me, because hell, here I'd thought it was just the office culture and now it turns out I've been biting my tongue on all those "that's what she said"s for nothing. I can also see how someone else would find it obnoxious, unprofessional, or remniscient of more serious harassment. Or be okay with double entendres but not want to be party to in-depth discussions of Scarlett Johansson's figure. Mixed company is a funny thing; my friends and I are a pack of filthy-mouthed guttersnipes amongst ourselves, but we often dial it back if there are guys in the conversation, because chances are they don't want to hear us talking about David Tennant in more-or-less the same way they talk about Scarlett Johansson.
So basically... aside from 100% unacceptable behavior that you shouldn't be playing silly-tie games with in the first place, it's not about automatically scrubbing all your language squeaky-clean, it's about finding a dynamic that your original team and your new employee both find comfortable for mixed company and making a good-faith effort to respect it.