A retarded exclamation point is the random numeral "1" that is mistakenly typed at the end of an exclamatory sentence when someone accidently lets go of the "Shift" key while trying to type an exclamation point (!) on a keyboard.
Dude One: Guess what I did last night Dude Two: What?
Dude One: I got some of Trisha's sweet ass
Dude Two: WHAT1
Dude One: Huh? What the hell does "WHAT1" mean?
Dude Two: Oh, sorry man...retarded exclamation point.
A chicks vag and asshole combination package makes an exclamation point (!). Notice the line (vag) and dot (anus) and separation of the two entities (taint).