flip flops at the office? That's a pretty great work environment you have there. I recall once where I had just flown back from Asia on a trip and instead of driving home I just went to the office since my flight arrived at 3am and work starts at well, you know. They had showers in the building and I had 24 hour access with a security card so I just got a few hours sleep on the sofa in my office.
I had purchased custom made suits while visiting Thailand so I was dressed really nice the next day with one exception. I only had flip flops because the only shoes I brought with me on that trip fell apart while I was traveling. While I wasn't reprimanded for this it was frowned upon and I just think that is a shame.
The place I grew up in referred to them as "thongs" as well. I can't be certain because i was so young but I don't think that sort of underpants existed yet and why they decided to name either of the products that is a bit of a mystery as well.
I think they just called a g string back then! That is too bad they weren't a little more understanding.