#define BUTTON D7

int lastState = HIGH;

void setup() {
  pinMode(BUTTON, INPUT_PULLUP);
  Serial.begin(9600);
}

void loop() {

  int currentState = digitalRead(BUTTON);

  if (lastState == HIGH && currentState == LOW) {
    Serial.println("Ouch, that hurts!");
  }

  lastState = currentState;
}