What can you do?

What can you do when someone calls like this?

Table "STT 3553439 - 1" Seat 8 is the button.
Seat 1: TumTiddle (1672 in chips)
Seat 4: Natalie83 (1867 in chips)
Seat 7: Owenben (2159 in chips)
Seat 8: pekar (1806 in chips)
Seat 10: Kingcod27 (2496 in chips)
Kingcod27: posts small blind 300
TumTiddle: posts big blind 600
----- HOLE CARDS -----
dealt to TumTiddle [7c 9s]
Natalie83: folds
Owenben: folds
pekar: folds
Kingcod27: calls 300
TumTiddle: checks
----- FLOP ----- [9h 4h 5s]
Kingcod27: checks
TumTiddle: bets 1072 and is all-in
Kingcod27: calls 1072
----- TURN ----- [9h 4h 5s][7s]
----- RIVER ----- [9h 4h 5s 7s][6s]
----- SHOW DOWN -----
TumTiddle: shows [7c 9s] (Two Pairs, Nines and Sevens, Six high)
Kingcod27: shows [Ks 4s] (A Flush, King high)
Kingcod27 collects 3344 from Main pot
----- SUMMARY -----
Total pot 3344 Main pot 3344 Rake 0
Board [9h 4h 5s 7s 6s]
Seat 1: TumTiddle (big blind) showed [7c 9s] and lost
Seat 4: Natalie83 folded before Flop (didn't bet)
Seat 7: Owenben folded before Flop (didn't bet)
Seat 8: pekar (button) folded before Flop (didn't bet)
Seat 10: Kingcod27 (small blind) showed [Ks 4s] and won (3344) with A Flush, King high