Leave your good shirt in the hamper.

Forget what you know about first dates. Cancel your reservation at the gastropub. Leave your good shirt in the hamper. Don’t even think about manscaping.

If there’s a chance you’ll be engaging in prolonged amorous congress with a perfect stranger, there are a few things you’re going to want to know about them first, and a full Saturday night of Back to the Eighties karaoke at On the Rocks Cocktails in Chula Vista will elucidate all of them.

For starters, how does your beau nouveau drink? With mini-pitchers starting at $4.75 and fierce wells at $3.50, you’ll quickly learn if you should anticipate notes of bile and shame on your prospective paramour’s breath every Sunday (and occasional Thursday) morning. Conversely, their endearing but firm two-drink limit may ultimately transpose your love of a good (cheap) bourbon into a ruthlessly scapegoated “drinking problem.” Avoid this.

How old is she, really? A lady never advertises her age, but there’s no arguing with the numbers behind a casual mention of her dormitory days when “The Killing Moon” drops. You dog.

Is he man enough? Take note of your suitor’s demeanor when he meets you at the dodgy strip-mall bar hidden behind the Denny’s. Do his lower eyelids tense in fear when he sees the 20+ security cameras leering at the bar topped with handbills declaring (perhaps self-consciously): “Just a fun safe place to party”? If so, split. He’s a bedwetter.

Is your date a genuinely fun person? Because that’s the whole point, isn’t it? Do you really want to be emotionally responsible for someone who can’t cut loose for a group massacre of “Pop Muzik” (seriously, they have 16 cordless mics) while tossing around bits from the lounge’s assortment of funny hats, boas, and tambourines? The answer is no.

Finally, is your gentleman caller a cheapskate? On the Rocks (celebrating three years on March 25, by the by) is about as grassroots as it gets, so a snubbed gratuity here only means disgrace when he gets around to taking you on a “real” date. Don’t be a victim.

All told, you really can’t go wrong with a bar whose claim to fame is an annual pimp and ho party, but play your cards right and you may even waive the cardinal rule of first dates altogether. Just don’t forget to call.

Capacity: 115 people

Hours: 10 a.m. to 2 a.m. daily

Cash only