He goes unconscious and wakes up hours later with the pickles staring at him with an air of victory upon its label. The pickles inside swirling with the residual magical energies, taunting him.
The goal was to open the bottle. He failed.
The consequences should match the importance of the contest. In this scenario, I'd say that not much would happen. It would be silly to take consequences at all, so he'd do a huge spell, fail, get taken out and choose not to take consequences.
The GM and the player would decide the best take-out result for the scenario. Probably, they'd agree that he'd have a head-ache and then he'd break the jar open by smashing it on the ground.
If he needed to open the jar before a horde of Outsiders came crashing in, I'd say the take out should fit the scenario so, maybe, he'd remain unconscious until the outsiders were breaking in, wrecking havoc.
And then the real conflict would begin.