In the time when one was of a certain age.

Intensifier. / Euphemistic shortening of "fuck you and the horse you rode in on"

Currently taking place.

(accounting) A method of inventory accounting that values items withdrawn from inventory at the cost of the oldest item assumed to remain in inventory.

One behind the other. / Together.

In large numbers, or great crowds.

Alternative spelling of in vitro (as attributive adjective)

(intransitive, idiomatic) To fail disastrously.

To speak to someone in private.

(idiomatic) Thoroughly; including every detail; with all particulars. / (military) By engaging small sections of an enemy army rather than fighting a single pitched battle against the entire enemy force.