If it upsets her.....STOP.....there is no point in annoying her unless you ARE trying to drive her away.

Immature actions especially if the other person is a more serious type will make them get sick & tired of you & they will leave & then you will be sitting there scratching your head

Honestly, the older people get who try to continually act childish are not looked at that kindly by the people closest to them as it does become totally irritating after a very short while.