hey, i was just wondering if you could use a BB tool on the rear cog lockring. i have a BB tool but not a lockring spanner. thanks

That depends on which BB tool you have. If it has an end that looks like the tool pictured below and fits, you can use it.

I assume you mean a BB lockring spanner, and yes you can, but it's not a good fit. I've damaged fixed cog lockrings when I used a BB lockring spanner, because it does not fit flush in the notch. Over the long run, you'll be better off getting a proper cog lockring spanner, such as the one made by Hozan.

on a side note the hozan wrench is just wide enough that can also be used to flip burgers in a pinch if you're grilling in the middle of nowhere and forgot a spatula

You can use a Trixie as well, but the burgers won't be suitable for a NJS-sanctioned event.

okay, i have one like the one scrodzilla posted. i think i will just look around and see if i can borrow an actual spanner for fixies from someone. thanks guys

Er, if you have the Park HCW-17 like Scrod posted, then that IS the correct spanner for fixed cog lockrings.

https://www.parktool.com/product/fixe...-wrench-hcw-17

Yep.

I use this: