Murphy’s Law applies to a situation where whatever can go wrong will go wrong. “My Boss’s Daughter” is the illustration of Murphy’s Law, only on LSD. Everything can go wrong and it does go wrong. Very wrong.

This movie illustrates a vital concept. Ashton Kutcher could not play the straight man in a slapstick comedy. Not only should he not be here, but no one else should, either.

A company brown-noser thinks he’s going out on a date with his boss’s really hot daughter. In an awkward realization, he finds out she asked him over to house-sit her zany dad’s pet owl named O.J. so she could go out for the evening. In doing so, he keeps getting himself deeper into trouble in this endless storm of unwanted guests and messy situations.

And some corporate suit was sitting in his office with a line of cronies at each side and said, “Yep, that sounds like a good idea”?

Such is how a movie like “My Boss’s Daughter” gets made. The only good that can come from this is that J-Lo and Ben can take comfort in knowing their self-love gag-fest “Gigli” wasn’t the worst movie of the summer. At least “Gigli” is the kind of trash you can make fun of.

“My Boss’s Daughter” unbearably drags. Problems start with Kutcher.

He doesn’t have the acting chops to do anything more than run around like a belligerent maniac, which has made watching him in the past amusing.

Kutcher is always unconvincing in the lead role. Comedy is tough stuff, and just as dramatic acting, one needs to listen to his or her fellow actors in order to make it work. Kutcher seems to think nervous laughter and a cute grin can get him far — and it does in his own element, “That 70s Show,” where his character has a supporting role.

The audience is expected to watch him go from scene to scene as things unrelentingly get worse to the point where only a complete idiot wouldn’t have done one of three things: Call the police, leave the house or think of the quickest, least painful way to kill oneself.

Because, after all, we’re to believe he’ll do all of this in effort to impress Tara Reid — which is a task made understandable if you dig fake-baked 27-year-olds who still live with Daddy.

But I won’t blame it all on Kutcher. The real problem with “My Boss’s Daughter” is its unbelievably bad script penned by David Dorfman (“Anger Management”).

The script, packed with tired jokes and hidden-meaning racist puns, doesn’t go anywhere. It completes itself with a moment primed for “Full House,” backed by the laughable, tearful confession of Reid’s character that Pa, played with dull contempt by Terence Stamp, cares more about an owl than his son and daughter.

The scene provides the moment where if you have made it this far and have strayed away from vomiting, then my friend, open wide the floodgates you have kept shut until this very instant.

Perhaps its biggest flaw is its label as a romantic comedy, because it is void of both romanticism and laughs.

Maybe if you like owl jokes, “My Boss’s Daughter” is for you. Otherwise, you’ll agree — a much better idea would have been to film how the producers, Kutcher among them, could have convinced a studio to bankroll millions of dollars for such a tired and lifeless movie and still expected audiences to enjoy it.

Now that would be funny.