The grundlefinger can be any meta carpal used to massage or tenderly probe the grundle area. Also any person who resembles a small monkey. In portugal it is a common insulting hand gesture
Hey. Get that there grundlefinger out of my gazpacho! After that d bag cut me off in traffic I gave him the old grundlefinger.
common name for exceptional male genitalia
sorry I have to go report to the commander in briefs