WALL OF TEXT INCOMING. Not strictly a non combat encounter, but an apprentice enchanter tasked our party was with rescuing his master from his workshop/complex/whatever after an earthquake set off its defenses.
The first room was a dining room with places set for ten. Our barbarian grabbed a piece of chicken and was immediately attacked by the cutlery. The only way out was to sit down and have a proper meal like civilized adults. Most difficult encounter ever. Barbarian took 20 damage from the cutlery and 10 more from eating the chicken before our cleric purified it.
Second room was a small circular room with a mirror in the middle. Each member of the party is teleported into their own instance. The magic mirror brings their reflections to life. Each reflection believes they are the real one, and believes the only way out is to kill the actual party member.
Each instance was played out one on one, without the knowledge of the other players. DM took the role of the reflection. This is how they played out as far as the party knows.
Cleric (me): After a brief, cordial conversation with his reflection, cleric and the reflection reason they both can’t be real and fighting would be pointless (high AC and terrible luck with attack rolls). Both cast dispel magic, real cleric is free to move on.
Bard: Claims she was able to trick her reflection back into the mirror "oh no there's a bug on you" shove. Party is convinced that she seduced herself.
Rogue: evicerates her reflection without a second thought
Barbarian: Reflexively punches his reflection. reflection responds with an axe to the chest. Real barbarian barely survives the first hit. Gets 20 on his attack roll, decapitates reflection.
Monk: beat his reflection with feats of strength, wrestles it back into the mirror
Wizard: After her and her reflection fail to blow up the mirror, Wizard blows up her reflection.