There has lopng been a tradition of opening at the 3 level with a weak hand to interfere with your opponents bidding.
Open in a suit at the 3 level to show 4-9 points and a 7 card suit. This is particularly effective if partner has already passed, but be cautious if partner has yet to bid/pass. partner will normally pass, and needs 16 points to respond. Your opponents may well bid or double . Raise partners pre-emptive bid with 3 or more trumps and few points because your opponents must have a game in their suit.