What are some nice bait lines?

By bait I mean gambits which are very generous and nonobvious.

We probably all know the Legal trap, where you sacrifice the queen for... checkmate.

Another well known bait line (which is very unsound) is the Traxler Counterattack:

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5

which leads to chances for both players (but much rather for White)

I have recently studied a variant called the Caveman Caro-Kann, where White lures Black to take his rook and works from there, getting very tricky positions. The engine does not think very fondly of it, but play is very hard for Black. If I am not mistaken, if Black takes the rook, he cannot rescue his queen, but he trades it for 2 rooks and 2 pawns (which is very much okay), but his position has weaknesses, which will decide in human play. Also most humans will try to rescue the queen, which leads to pain.

1. e4 c6 2. d4 d5 3. e5 Bf5 4. h4 h5 5. Bg5 Qb6 6. Bd3 Bxd3 7. Qxd3 Qxb2

Another line is the Muzio Gambit, a variation in the King's Gambit. Best used if you know your opponent has heart problems. You can even sacrifice your Bishop on f7 aswell. Heart attack guaranteed.

1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Bc4 g4 5. 0-0

Do you know some very generous lines, which are actually very toxic?

From's Gambit would be one. If you are black and your opponent moves the f pawn then you sacrifice a pawn in exchange for quick development and if your opponent isn't careful you can give checkmate very quickly.

1. f4 e5 2. fxe5 d6 3. exd6 4. Bxd6

Also if you are playing against the kings gambit one trap is to decline the gambit and bring your bishop out. Some players will think they can simply take your e pawn for free although if your opponent takes it you can check your opponent with your queen and you will either win your opponents rook or deliver checkmate next move.

1. e4 e5 2. f4 Bc5

Also if your opponent plays the blackburn shilling gambit you can play a piece sacrifice gambit by accepting the gambit and then when the black queen comes out checking your opponent with your bishop, and then castling, and then advancing your pawns and getting your pieces out. You will be dawn a piece but have two pawns, and control of the center with the enemy king being in the center unable to castle as compensation. It tends to be easy for black to blunder in this line.

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4 4. Nxe5 Qg5 5. Bxf7+ Kd8 6. O-O

@Vertonghen I learned that line from NM-jerry's youtube channel @Chess-Network

And I would say I've made over 20 or 30 mates with that.

Now this one I'm posting is a sneaky way for white to win material in the opening. It can also work in the karokan depending on black's move order. I've had this work on player with ratings up to 1900 :

I play the Geschev gambit (or a variant thereof) against e4 quite frequently. It is usually accepted and works pretty well. With careful play White should win easily with the 2-3 pawn advantage, but Black has a strong initiative and I have pretty respectable win rates with it.

It's basically a better version of the Danish gambit, except for Black.