When your girlfriend is better then the best.
“My girlfriend Andrea is the bestest on the world!”
People named Luke are categorically the best
Luke is the bestest boyfriend with the nicest butt.
Better than best, fantabulous, extraordinary, swappa.
"The teacher received many amazing gifts in one day and had trouble discerning which gift was bestest."
In baseball, compared to Aybar, Jeter is the bestest.