Trash is played over opponents' notrump openings. After 1NT:

dbl - for penalty

2C - transfer to diamonds, or 10 cards in hearts and spades
2D - transfer to hearts, or 10 cards in spades and clubs
2H - transfer to spades, or 10 cards in clubs and diamonds
2NT - transfer to clubs, or 10 cards in diamonds and hearts

After advancer (the overcaller's partner) accepts the transfer:
pass - weak one-suited hand
next suit - weak two-suited hand
raise - invitational one-suited hand
jump shift - invitational two-suited hand
(Note: no hand should be too weak; this is an overcall after all!)

2S - 10 cards in clubs and hearts, or 10 cards in diamonds and spades

Advancer bids 2NT to find out which hand; with the round suits (clubs and hearts) you will rebid 3C. With the pointy suits (diamonds and spades) you will rebid 3D.

With very strong hands you can make the Trash bid one level higher. Or if advancer is very strong he can accept the transfer by bidding one level higher, or by refusing to accept the transfer (e.g., 1NT - 2C - P - 2H or 2S or 2NT or 3C). If you find requiring 10 cards for the shape bid is too restrictive, you can agree instead that a shape bid shows at least 9 cards in the two suits. Source: Wayne Pollock