It was beginning of their first year of +2 i.e standard 11'th.

Taehyung was filling the form of his ID card when an idea popped into his head...he was just 16 at that time and was going to hit 17th that year but in his form, he mentioned his age 18 yrs.

If he'll be caught, he can make an excuse that it was by mistake and if nit caught, its a victory for him.

After submitting his form when he was coming back, he saw that Jimin too was filling his form. Jimin saw him and smiled at him.

"Jimin, listen can you make your age 18? Please!-"

"but why tae?"

"I'll tell it later"

"but-"

"please baby"

"uhh um okay "