Grob's Gambit Accepted

Black "accepts" the gambit by just taking a pawn. White usually continues with two moves:

3. c4

c4, the Fritz Gambit is another move where white gambits a pawn. However it's tricky - after dxc4 white can play Bxb7 and take the rook in future. But this is risky situation, because you don't really have a continuation after fourth move.

3. c3

This is more solid move. It doesn't create any attacks but helps to develop and play d4 in future in order to create a good pawn structure to complete development later. But don't forget that your kingside is damaged.