You two took missions very seriously, him more than you usually. However, you irritated him earlier, so this mission, sense it was not a dangerous one, he purposely lacked being serious.

Rather than silence, he continued on and you snapped, "we work in silence!"

it seemed to hush him... until you heard the familiar sound of a soda bottles cap coming off, the usual noise after and you glared at him and he just gave an innocent smile,

"what? I was thirsty." he replied, grinning