Most stuck I've ever been was at Pismo. I was ALMOST to the top of what seemed like a fairly easy-going hill, but it was really soft at the crest. Once I was stuck down to the frame I had no choice but to dig myself free, before a snatch-recovery. I got to endure about a hundred peeps roll up to remind me to air down.
I was only air'd down to 20 PSI. Wheels are 18s, so I was nervous about going down to 10-15 which would have been totally fine and saved me about 45 minutes of digging with an e-tool.
AIR DOWN, DUDES!