Chase and Dustin were sitting by the PCA pool one day.
"You know Dustin, I love how you enjoy hanging out with the big kids here at PCA".
"Thanks Chase. Well, I can't help it. My sister is awesome, which makes her friends awesome."
"Aww thanks Dustin" said Chase and he scooped him up in his arms for a hug. While hugging him his fingers accidentally scraped his ribs, making Dustin giggle.
Chase wanted to see how ticklish Dustin really was.
What does he do?