Recently, we explored why Millennials buy the things they do. All else being equal, if you want to sell to this generation, you should build the idea of convenience into your product or service.

With that in mind, meet Stephanie. She's 24 and lives in New York City. She goes to a friend's apartment. They open a bottle of wine and watch some Netflix. As she gets up to leave, she feels her phone buzz.

It's a notification from an app called Venmo. Her friend has just billed her $6.

Meet Venmo

"I couldn't believe she was charging me for the glass of wine she poured me herself," Stephanie told Kari Paul of Quartz for a recent article. "Venmo is definitely giving some people an easier outlet for that kind of behavior."

Venmo, owned by PayPal, connects users to each other's bank accounts and makes it easy to ask people for money, instantly. Launched in 2012, it takes its name from the Latin word vendo, for "to sell."

"We liked [the name] because it was short and made for a good verb: 'Just Venmo me for dinner,'" founder Andrew Kortina said on Quora in 2014.

But now, it's more than dinner. As Paul writes (or at least the headline of her article reads), "Venmo Is Turning Our Friends Into Petty Jerks."

"Nickel and dime ... without confrontation."

Of course, it's not only Millennials who use Venmo--but some have suggested that's the main user base.

"Some young people are finding that the app's convenience--and the faceless nature of requests--has emboldened the tight-fisted among us to nickel and dime close friends without confrontation," Paul writes.

Paul's article is largely autobiographical.

First, she says a friend Venmoed her $4 for the difference between a drink she'd bought the friend and the one her friend had bought her. Then she and another friend Venmoed each other back and forth, working out the $2 difference between the cost of the drinks and the cab ride they'd shared.

She continues:

Similar stories abound. One Venmo user told me that a co-worker had invited her to coffee, only to request $3.79 in reimbursement afterward. Another said her roommate charged her $3.32 for a shared garden rake.

"When he moves, am I supposed to ask for my $3 back?" she asked. "Venmo is making everyone stingy and strange."

Unless, maybe, the problem is people ...

There are other similar competitors--Chase QuickPay and Square Cash--and they've solved some age-old problems. Anybody who lived with roommates back in the day remembers going through your shared phone bill, trying to figure who owed what.

If behavior has changed, however, not everyone thinks it's the technology at issue. Writing on Deadspin, Giri Nathan says it might be more that Venmo and its ilk could just be drag[ging] "to the surface whatever petty resentments were lurking all along."

What do you think? Is Venmo the app we've been waiting for to make check splitting easier, or is it insane to invoice your friends for a $3 cup of coffee? Let us know in the comments below.