Sounds like you are only surprised at the opening because you didn't investigate and had odd assumptions about two old ladies movies that were before my time. How old are you and why don't you keep up with movie trends if you are a geek under the age of 45 years old?
The whole "raunchy bro movie" trend is a huge thing right now and now they are giving women a shot to do their own version of those. As a matter of fact, the movie looked like the R rated female starring version of Will Ferrell and Mark Wahlberg's 2010's "The Other Guys," not a Bette Midler or Kate Hudson's mother comedy. Bridesmaids only opened with 26mil, it's legs are what got it the big numbers so how big was that idea before word of mouth took hold? The opening was good but hardly groundbreaking for such a "universal" idea. The legs made the movie the hit it was. Also Melissa McCarthy has become one of the most popular comedy stars in just a few short years after her break out role in Bridesmaids and just had a hit earlier this year, you should at least remember her name because she is a big reason why the movie did 13.6mil yesterday.
The cop comedy The Other Guys, which teamed up two big stars opened with 35.5mil in 2010 and earlier this year Identity Thief starring McCarthy and Bateman opened with 34.5mil. Bateman is a funny guy but he wasn't the main reason for those numbers. (The Change Up anyone?). In 2009, Sandra Bullock starred in The Proposal which opened with 33.6mil. Now I expect that the audiences for all these comedies overlap. All those movies have something in common. Hot stars+pleasing concept+decent marketing and The Heat has those things. Add in 2012 ticket prices and that equals a 35-40mil opening, it equals at least a 35mil opening weekend.
I was a little surprised by the so-so marketing campaign for WHD. It feels like Sony got too cocky about having Tatum and Foxx in their film since the two men were coming off of big hits and the elephant in the room remains OHF which opened with 30mil and made 98mil total. Snow White and the Huntsman did way better than the first Snow White movie, Mirror Mirror, because Mirror Mirror was a completely different genre, had a terrible set of previews and disappointed. Unfortunately for WHD OHF is not in a completely different genre and it over performed in every way possible so the same situation as last year had less of a chance of playing out. And here we are, a 9mil Friday for WHD in comparision to OHF 10mil. WHD will be lucky to do 25mil over the weekend.