Seojun taught Dongwoo the act of self-defense, one very likely to work on his uncle.
Of course, they hadn't been having just fun since their uncle showed up. Scared he may hijack Dongwoo when they least expect it, they decided to help him prepare.
Since Seojun was more familiar with his uncle's 'tricks' he decided to teach Dongwoo to perfection.
For days, after dinner, they would stand in the living room with Seojin holding a little dildo in place of a gun.
Dongwoo laughed a few times saying,
"This is so ridiculous." He laughed. "Couldn't you have gotten a toy gun instead? I mean," he flicked his fingers at the dildo. "It's hilarious."
"It's better than a toy gun that could bring implications, Hyung." Seojin said. "Now, focus. Matteo is going to reach you the ropes."
Dongwoo nodded and turned his head to Seojun who was analyzing from the side.