In the early 2000's, my BFF was in her second year of university as a mature (24 year old) student, in Brighton. I had been dating a new man (now DH) for a few months and we arranged to go and visit (staying at a nearby B&B) for the weekend. DH was in his NQT year of teaching and I was working as a Finance Administrator, so neither of us were earning a fortune, but we figured we had more cash than my student BFF.
On the day we arrived, we met at the pier and went for lunch at a restaurant of my friend's choosing - I'd offered to pay as a treat for her. The place she chose was really pricey (for us!) and I ended up paying nearly £100 for lunch for 3 of us.
We decided to while away the afternoon in a pub, where DH and I alternated paying for rounds. I was drinking vodka and Diet Coke, DH was on pints, but my friend was on the vodka and Red Bull - which was extortionate, at £6 a time! DH and I decided that it was our treat, we had offered, I didn't see her terribly often, I really missed her and she was a poor student! We spent a fortune, but we had a fab time and my friend was grateful, saying: "Thank you so much for this guys - there's no way I could afford lunch out and an afternoon in the pub, I really appreciate it!", and we were having such a wonderful time - it was my first time introducing DH to BFF, so it felt like money well spent. I knew I'd have to tighten my belt for the rest of the month, as I'd already spent most of what I'd budgeted for the whole weekend!
It was coming up to 6pm and we decided to move on to a different pub. My friend asked if she could quickly pop into Boots as it was en route. I went to go in with her, but she kind of insisted I wait outside with DH, so we decided to take the opportunity to have a cigarette while we waited as she said she wouldn't be long. By the time I'd finished, she was still in the shop, so I decided to go and look for her.
I eventually found her in the Dental section. In her hand was a teeth whitening kit - worth £40! But that was not all.. at her feet was a shopping basket, containing a bottle of Ralph Lauren perfume (£50?) a Max Factor mascara (£10) and a large bottle of multivitamins (£10) and a huge box of Berocca tablets (£10)
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BFF was like a deer caught in headlights when she spotted me - she knew she had taken the piss. I just told her to get a move on and she said she'd already paid for the perfume at the Fragrance counter, that it was a birthday present for her DM (buying your DM the same perfume you wear - how stupid did she think I was?!?), and she was "just looking" at the other stuff in her basket and had NO intention of actually buying anything... 
She did indeed leave without buying anything else, but when we got to the next pub, I announced "Your round then!" to her, and asked for a double vodka and Red Bull! We carried on in rounds, but with all 3 of us taking turns from then on - and I moved back to Diet Coke mixers! I didn't tell DH about what happened in Boots that day, cos I was so keen for them to like one another and she wasn't usually such a Cheeky Fucker - she'd clearly been saving it up for my visit! 