The combination of mentally and physically losing it. To 'tweak out' or 'freak out' from a stressful situation or an exciting situation. Kibbyin can be a great, hilarious scene if you are overcomed with joy and overstimulation that your body cannot handle. People and Animals often kibby out daily!
"As soon as my cat got a hold of the catnip, he started kibbyin' out!" "The mere thought of her wedding invitations alone made the bride-to-be kibby out!"