“Tropic Thunder:” I guess you had to be there.

Ah, the things an actor will do for a Teen Choice Award.

Like, for example, trek through bug-infested jungles with nary an iPhone for comfort, facing unfathomable perils in the vein of, say, cuddly panda bears.

That’s the premise of “Tropic Thunder,” a Hollywoodland mockery of the entertainment industry that leans on big names and bigger explosions to compensate for comedy that is mostly mediocre.

It’s another R-rated summer attempt at laughs that came oh-so-close, yet is still so far from a hit.

“Thunder” follows the cast and crew of a film about American heroes on a near-suicide rescue mission during the Vietnam War. Heading the cast are fading action flick juggernaut Tugg Speedman (co-writer/director Ben Stiller) and Kirk Lazarus (Robert Downey Jr.), an Australian method actor who underwent a controversial skin-darkening procedure for the role.

They’re spoiled and failing: five days into shooting the project is already a month behind schedule, thanks in part to the prima donna rivalry Kirk and Tugg have developed. These are guys who do, after all, equate having TiVo with clean water and a roof overhead.

Sent off the grid, deep into the jungle where personal assistants holding Evians and Blackberries are nowhere to be found, Tugg and Kirk begin what they think is a gorilla-style shooting of the film, replete with realistic ambushes to heighten their performances as well as those of fellow cast mates Jeff Portnoy (Jack Black), Alpa Chino (a very funny Brandon T. Jackson whose presence holds its own even against Downey Jr.’s) and Kevin Sandusky (Jay Baruchel).

But what starts as a movie capturing its actors drooling while crying and pulling Christ-like poses as they’re hole-punched with bullets just to earn that Oscar nod soon becomes a movie-within-a-movie when they find themselves unwitting targets of real-life, gun-weilding drug lords.

From its start “Tropic Thunder” is full of blood, sweat and grime; Jack Black even completes a scene sporting grossly leftover vomit on his face.

It’s also full of cameos — some longer and more hilarious than others — including Tobey Maguire, Tom Cruise and Matthew McConaughey.

But what at times is laugh-out-loud hysterical seems at others to be one large “I guess you had to be there” joke.

The screen is a bit overcrowded, with Cruise’s overweight, cursing studio exec pitted against the over-the-top deliveries by Stiller and Black.

But the comedy, almost in shock jock form, still pulls through on occasion, creating an intermittent gut-buster with shortcomings mitigated by a host of recognizable faces making fun of their own. While most films depend on an actor’s ability to blend into a role, spotting the celebrity becomes — for better or worse — half of “Tropic Thunder’s” fun.

And while Cruise’s booty-shaking dance over the ending credits is so ridiculous you can’t look away, the compensation doesn’t go far enough. The posturing and drollery is

quickly forgotten, as is — whether or not it should be — the soured view of an industry that, like the film depicts, spends millions on a single shot in the name of escapism.

“Tropic Thunder” pulls a few funny punches, but for the most part is a wash out.