to be persuaded; to "better believe it".
This is an irregular form used in active voice, object focus only. It may have been the base stem of this word at one time,
but it now takes no affixes, and kahagad appears to be the base form at this time. The ka- may have originally come from maka- "to be able", and is often translated that way.
You be persuaded, don't go.
You had better believe it, don't go.