The Trials of Glarb (or Love Games) of ancient tradition is a competition held in the Slime Kingdom to prove love. In the episode "Love Games," Finn and Slime Princess compete against Blargetha and Guillermo (Blargetha's fake husband) to determine which of the two sisters will rule the Slime Kingdom.
The couples get on the swan boats and croon for each other in the lake. The most loving and heartfelt song judged by the host wins. Finn sings "I Just Can't Get Over You" to win the trial.
The big spoon puts his arm around the little spoon and cuddles on the futon. The host watches the couples spooning, measuring and assessing their love by posture and overall vibe. The best cuddle, or spoon, wins.
Little is known about this event since Finn bails out of the Trials after spooning. It was scheduled to take place the day after crooning and spooning. Judging by the name, it involves kissing.