When Jackie and the Forman's head up to her Dad's cabin to move out all the stuff, she lies to Hyde and tells him that she's going to a doll expo, but she assumes that he "knows what she really means".
Fez, Hyde and Kelso decide to head up to the cabin and have a party. When Kelso discovers the "place that can eat his hand" for his hidden stash, the Forman's pull up and Kelso desperately attempts to hide the stash in a vase, only to discover that he can't remove his hand.
The other story sees Eric and Donna driving in a seperate car towards the cabin (and experimenting with a few carnal pleasures along the way) but end up getting lost and have to rely on Jackie's "expert" directions to get them there, and they argue along the way.
Kelso finally gets his hand out of the vase, but not without alerting the Forman's to his stash. After trying to pin the blame on everyone, Jackie takes the rap, but Kelso is Kelso so he gets pointed out anyway due to his own, well, Kelsoness.
The end with Eric and Donna doing it on the Forman's table and the expression on everyone's face is classic and really helps make the show.