I just got a new bumper and want to reinstall the badges from the old bumper. Does anyone know what kind glue or stuff to use?

 

What you need is called moulding tape. most places carry it. I just bought some last night at NAPA but auto zone schucks/checkers carry it too.

Some parts stores sell glue but it is permanent.

I got bored and debadged my car. Then I used the "s" from the sides to cover the holes from the honda badges on the front and rear.

 

Rick's badges sit very flush as the adhesive is impregnated into the back of the badge. Using the double sided auto trim tape may leave the badge "raised" slightly. You may not like this.
May I make a suggestion? Get a piece of 3M Scothcal film that is slightly larger than the badge. Get the thinnest you can find (6 mil? thinner if you can find it). Brush on a thin layer of contact cement on both the top side of the film and on the under side of the badge (as per the cements instructions). When it's time (tacky), apply the badge to the film and put a small weight on top of it on a flat surface for about an hour to let the cement set. Then carefully cut the excess film away so it's the same size and shape as the badge. Peel off the backing and stick onto the car like you did when the badge was new.

 

or... just buy new ones...

 

New Rick's badges ................. must buy a pair for $68.00, add in shipping, tax, wait several weeks.
Re-using the old one (assuming it's in good condition still) ...................... can find a piece of 3M film for FREE, contact cement most likely already at home (5 bucks if not), a bit of running around to get film (and cement), a bit of time to install.

Buy new ones? ...................... Sure, why not?