This phrase is often doubled: "for days and days" to stress an even larger period of time or amount of something.
(Usage Note: In Northern California, this is often paired with the word "Hella" to add even further emplasis)
2. "That chick's legs went on for days!"
3. "This party's going to be hella tits for days and days!"
"Look at this backroom, we got soup for days!"
"Damn, the line for this show goes on for days.."