The Rema (O.Ch. 428:6) writes, that for the תוכחה we don't call up by his name but we call up מי שירצה
The Biur Halacha writes that it doesn't mean that you call up "יעמוד מי שירצה" which has no טעם
(doesn't sound right) it means you call up by his name someone who has agreed beforehand and
is willing to be עולה .
It is interesting that in the olden days when people still believed in the 11th אני מאמין of שכר ועונש it was a scary
thing to be עולה the תוכחה. I haven't noticed today, the בעל קריאה (who usually gets the Aliyah) to be
scared or nervous during his Aliyah