Nonce

Someone overage who likes someone underage.

“Who is the nonce”
“Gylfi Sigurosson

A2

British an advanced level of a subject taken for the General Certificate of Education, forming the second part of an A level course, after the AS level

A2 seemed the most promising

A1

In good health;physically fit

Are you A1

A1c

airman,first class

That guy is A1c