Ezekiel Elliott and Dak Prescott decided to take their guys trip to Florida to the next level -- by buying a bunch of penis squirt guns ... and rocking them to the nightclub!

Here's what happened ... the Dallas Cowboys stars rolled into Shorty's Market in Key West, Florida on Friday night -- along with several Cowboys offensive linemen -- and decided to arm the group with some water wieners.

We spoke with store employees who tell us the guys were super nice and made the purchase as a joke while they were bar hopping.

Witnesses say the crew ended up at Rick's Bar ... where Zeke was seen holstering his penis in a black fanny pack, with the barrel dangerously pointed up.

We're told the guys had a great time ... and no one got in any trouble ... and, if you're interested, Shorty's says they've got plenty more guns available for $14.99 a pop!