The last ole (person called to the Torah) (besides the maftir) of Vaychi, P'kude, B'chukosay, and Mas'e is, in my experience, called using the formula "yaamod p'loni ben p'loni sh'vii chazak", with chazak added at the end.
In some instances, a bridegroom called to the Torah on the Shabas before his wedding, or a boy his first Shabas of bar mitzva-hood, is also called as "yaamod p'loni ben p'loni maftir [or r'vii or whatever] chazak", with chazak added at the end.
- What is the provenance of these customs?
- What is their reason/basis?
And anything that can be said about their incidence/currency (who has these customs?) would also be appreciated.