import maya.cmds as cmds

def jpmColonBlow(depth):
	selectMe = "*"
	for i in range(depth):
		selectMe = selectMe + ":*"
		fuckUp = cmds.ls( selectMe, sn=1, tr=1 )
		for obj in fuckUp:
			newName = re.sub( ":", "_", obj )
			try:
				cmds.rename( obj, newName )
			except:
				print (obj + "\n")
				print "Renaming Error"

jpmColonBlow()