Paul Frank Calculator Watch
I'm guessing as soon as you see the Paul Frank Calculator Watch, you'll instantly be transported back to double maths at school.
Available in a range of colours, from a manly dark green to a girlie pink, the watches have all the functions you'd expect of a digital watch (time, date etc), but add to that a fully functioning calculator (like the Casio you probably had as a kid), water resistance and of course, the Paul Frank retro styling.
You can pick one up for $75 (around £40).
Find out more at the Fred Flare site