Michael’s is an overcall in the Opener's suit (cue bid) to show a two suited hand.
The Michael‘s convention can be used with a weak (6 - 10 HCP) or strong (16+) hand but not with an intermediate hand.
If the overcaller bids at 2 level over opposition’s minor suit such as 1C - 2C or 1D - 2D, then the overcaller has 5 cards in both majors.
If the overcaller bids at 2 level over opposition’s major suit such as 1H - 2H or 1S -2S, then this shows 5 cards in the other major and a minor suit.
If your partner uses the Michael's bid, you must respond however weak your hand.
Response to 2C or 2D
2H or 2S - a long major with weak hand
3H or 3S - 3 card support and at least 10 points
3C or 3D - a 6+ minor with no 3 card support in a major
2NT - invitation to game
3NT - Play
Response to 2H
2S - At least two spades and weak hand
3S - 4 cards in spades and at least 10 points
2NT - Ask for the overcaller’s minor suit
3C or 3D - 6+ minor with no 3 card support in a major
3H - Artificial bid showing interest in a slam in spades
3NT - Play
Response to 2S
3H - Sign off
2NT - Ask for the overcaller’s minor suit
3C or 3D - 6+ minor with no 3 card support in a major
3S - Artificial bid showing interest in a slam in hearts
3NT - Play
Michael’s is similar to the Unusual No Trump (UNT) overcall which shows the two lowest unbid suits.