URL: http://www.newegg.com/
Browser / Version: Firefox for Android 38.0.1
Operating System: Android
Problem type: Something else - I'll add details below

Steps to Reproduce
I reported this in March in Bugzilla 1144221. Newegg was unusable on Fennec at that point on 36.0.2 and it remains unusable.

Steps to reproduce :
Browse to http://www.newegg.com/
Click the "Computer Hardware" menu item on the left (or any menu item)
If it brings up the sub-menu click CPUs/Processors (or any menu item)

Expected Behavior:
Be taken to the Computer Hardware page or CPUs/Processors page

Actual Behavior:

HTTP Error 400
Bad Request - Invalid Header
The request has an invalid header name

This happens for any link clicked

Once this occurs, even browsing to http://www.newegg.com/ results in the same HTTP 400 error

I've observed this for as long as I can remember but only gotten to reporting it back in March.