Hand it to The Hangover. Without the over-the-top success of that over-the-top comedy a couple of years ago, movies like Bridesmaids and Bad Teacher and this one — the best of the bunch so far — wouldn’t be getting made.

Horrible Bosses is the latest in a series of unapologetic comedies — movies that throw caution to the wind and keep ramping up the outrageousness.

Truth be told, some version of a Horrible Bosses script has been kicking around for about five years. Director Seth Gordon, its fourth (uncredited) writer, has taken the script he was shown in a wilder, crazier and less forgiving direction.

But here’s the question kicking around in my head.

I saw the movie a week ago. Why are scenes from it still welling up and sending me into fits of chuckles?

It might be the story, brimming with universality, about three pals who regularly get together at a drinking hole to swap stories about how ridiculously awful they’re treated at their jobs. Or the inventive direction that has everyone in the perfect spot at the right time, saying their lines in the most optimum comic manner. Or the fact that the folks playing the three bosses of the title (Kevin Spacey, Colin Farrell, Jennifer Aniston) are in scenery chewing mode.

But between chuckles, I’ve given this some thought. The biggest laugh-inducing factor in Horrible Bosses is the chemistry.

Our three nice guy heroes, driven to look into ways to kill their respective bosses, are played by Jason Bateman, Jason Sudeikis and Charlie Day. Their separate situations aren’t very funny. Spacey emotionally tortures Bateman’s Nick. Ferrell, whose character is coke-addled and stupid, gets the blood of Sudeikis’ Kurt boiling. And whenever the sex-crazed Aniston comes near him, Day’s Dale could use a tamper-proof chastity belt. (Well, OK, that part is funny.)

But Bateman, Sudeikis and Day are funniest when they’re together, reacting off of each other. (Let us praise director Gordon for regularly keeping all three of them in one shot, sitting on a couch or crowded into a car.)

This is more than just good line delivery or picking up on someone’s ad lib. Bateman seems reasonable, Sudeikis seems calm, and only Day seems excitable, with his eyes going wide and his voice shooting up to mezzo-soprano level. But suddenly there’s more slapping going on than in your typical Three Stooges short. (According to director Gordon, none of it was scripted. And yes, grown men slapping each other has always made me laugh.)

There’s so much more. No filmmaker in his right mind would try to top Woody Allen’s cocaine sight gag in Annie Hall. But it works here, and then it reaches new heights. The same goes with an uncountable string of wrong time/wrong place coincidences. Normally that kind of thing would get tiring; here, it gives the film legs. Writers will often say that you can never go wrong with a funny name. Well, here we’ve got Jamie Foxx as a murder consultant who calls himself Motherf---er Jones, and that first name is used, repeatedly, in the most casual way.

This is a movie with no slow spots. It’s funny, then it’s nuts, then it’s funnier because it’s so nuts. I’m going to have to see it again just to catch the dialogue I missed while I was laughing.