sickest laydown ever

[johnsy]

just finished a good session at the $400 5-10 Hollywood park no limit game when i went over to a friends $200 table and saw a hand go down that i wouldnt have believed unless i saw it with my own eyes. Button is agro player. Overthinks hands and makes wierd plays. His opponent is a regular who is a mild donk. Anyway on to the hand.
1 ep limps. 2 lp limp. Button raises to 25 straight with red 7s. All fold to Lp mild donk.He calls. they are both about 900 behind.
Heads up to the flop of Kd 9c 7c.....60 in the pot
Lp donk bets $200 button folds faceup...WTF?
Now me personally i wouldnt have made this laydown. Whats your line and why? The donk showed his hand. Results to follow