As you might know, Solo changed the shape of its famous round cup a few years back. The company adopted a square design to help prevent the cup from sliding out of partygoers’ hands.

My experience with the iconic product wasn’t all that extensive until recently when I embraced the cup for its ease of use and 18-ounce capacity to avoid repeated trips to the coolerator.

I figured they’d solved the slip-and-slide mystery that turns a simple drink into a mess. But boy, was I wrong, at least in my case.

Picture this: I’m in my apartment, set to enjoy a full-sugar, ice-cold Pepsi-Cola. I fill the Solo cup with crystal-clear, commercially produced ice, pour in Pepsi fresh from the freezer that had almost but not quite reached Slurpee consistency, and fill the cup with cola goodness.

I reach for the cup, and Solo flies from my sausage snappers like a greased pig at a county fair. Next thing I know, Pepsi’s doing the cha-cha across my 18-percent gray, wall-to-wall carpet.

The redesign seemed to make sense: Square the cup, slap on their logo, and — for a laugh, I guess — throw in some pleasure dots. Like something you’d find on a … well, let’s not get into that.

For all I know, the improved design reduced most users’ butter fingering.

But guess what? My ham hands weren’t having any of it. Slip, drop, splash. Again and again.

When I thought I’d have to ditch Solo for good, I stumbled onto a game-changer. Before you pour in your poison, give that cup an outside rinse with hot water. This probably washes away some residual lubricant or antistatic agent left over from the factory.

So, try it the next time you’re ready to party with Solo — and banish those butterfingers quicker than you can say, “Last Tango in Paris.”