Today, Norwich Approach freq. Lady controller doing a fab job is dealing with two PPLs, one G-CS and the other G-CS.
ATC: G-CS, be advised similar callsign on frequency
G-CS: Roger, G-CS
ATC: G-SC, did you copy?
G-SC: Affirm, G-SC
ATC: And keep a good listen out, there will be a third similar callsign on frequency in a minute. A few minutes later-
G-BSSC: Norwich, good afternoon, G-BSSC.
ATC: G-BSSC use full callsign, two similar callsigns on frequency. Flight Information Service you have.
G-BSSC: Use full callsign, G-SC
... priceless in itself, but a bit later:
ATC: G-SC freecall enroute
G-SC: Freecall enroute, thanks for you help, G-CS Suppose you had to hear it to appreciate it, but it was probably the highlight of our very long sortie in the Norwich area! BTW, Norwich, if you're reading this- you know who we are, and thank you!