Mr Bosenka

We have a regular attendee at my shule minyan who joined us a few
months ago. Whenever the chazzan or the korei finishes, this gentleman
gives him a loud "Yasherkoyach Mr Bosenka"! Now I (and several others)
have tried to discover who Mr Bosenka might be, but MR Yasherkoyach is
not forthcoming.

Perhaps someone here can help. Who is (or was) Mr Bosenka? It's
driving me crazy (and as Hannies puts it, it's only a short walk, no
need to take a car).