The Rx for the Sept. 26 preem of “50/50” at the Ziegfeld was laughter – and lots of it.

Summit Entertainment’s dark comedy, based on writer-producer Will Reiser’s battle with cancer, gave Seth Rogen a chance to imagine himself without his curly locks.

“I actually shaved my head in high school … and it wasn’t pretty. My physical appearance got much worse,” joked Rogen. “My fashion sense isn’t much better. The last thing I bought was a strap-on dildo yesterday.”

Reiser quickly came to his pal’s aid and added, “He wears it well, though.”

Pic’s Joseph Gordon-Levitt explained it was his second time breaking out the shears. “I regretted it quickly as my head was so cold right away,” he said of his first exercise in bald.

— Joseph Barracato