Callsign used by a military commander or leader in radio chatter to indicate the acting commander is speaking instead of that platoons Radio Telephone Operator (RTO).

If command calls the platoon and requests "Hunter Two-One", they'll be hailing the unit Hunter Two-One, and will therefore speak to the RTO. If command calls for "Hunter Two-One Actual" they are requesting the acting commander of that unit, as opposed to the unit as a whole (and the RTO).

I couldn’t care less (but one must keep up appearances, right?)

A word that teenagers (in the UK anyways) feel the incessant need to use every time they open their mouths. It is a pointless and ridiculous filler and should be banned to prevent it spreading any further.

Examples of usage:

wtaf - what the actual fuck
omag - oh my actual god
bffal - best friend for actual life
istag - i swear to actual god
soab - son of an actual bitch
stafu - shut the actual fuck up

Slang for: Are you serious? Or are you kidding?

Boy/girl friend....in an actual relationship

The doing/being of actual.
Being actually serious.
No doubt.
100% serious.
If someone says their actual you should stop because it can kill you, the power of actual.