This is another commonly used phrase that's very similar to yesterday's expression. Basically, if you're picking up the tab for your dinner with friends, then dinner is on you. So when you're ready for the waiter to bring the check, you can either say, "It's ok guys, I'm picking up the tab," or "It's ok guys, this one's on me."
Like yesterday's phrase, this expression is also commonly used to jokingly tell people that someone is paying for the purchase. So if you're out to dinner with a bunch of friends, and one of them, say John, just got a promotion, you can make an announcement and say, "Don't worry if you forgot your wallet, this dinner's on John to celebrate his promotion."
Bill: Ok everyone, to celebrate John's promotion, this dinner's on him.
John: Hey, not so fast. The promotion's not final yet. Once I see the increase in my paycheck, I'll pick up the tab. But not tonight.
Bill: Ok then. Sam, this should be on you, right? Didn't you get a raise recently?
Sam: Well, yes I did, Bill. But I already picked up the tab last week. You missed it.
John: Actually, wasn't it your birthday yesterday, Bill?
Bill: Hey, nice of you to remember. Now, I feel special.
John: Good! Because this dinner should be on you to celebrate your birthday.
Bill: Alright, alright. I guess it's my turn to pick up the tab.
pick up the tab - pay for something (see yesterday's blog)
say - for example (see the June 30 blog)
Alright everyone, try to use today's phrase when you find a chance. You can say, "This one's on me," or "This dinner's on me," or simply "It's on me."
Enjoy the weekend. Have a fun and safe Fourth of July.