#2 Fouling the keeper
While more recent editions of FIFA do allow you to challenge the keeper during loose ball situations, fouls that occur at such times are more or less unintentional and receive a yellow card at worst.
However, back in the early 2000s, players could intentionally slide tackle the opposing keeper, often earning a red card in the process.
At times though, fouls were overlooked and goals could be scored once the goalkeeper had dropped the ball.
#3 Intentional diving
FIFA in the 1990s introduced the option to dive in an attempt to try and con the referees into awarding soft penalties and free kicks. While it was extremely successful to implement this successfully, some clever gamers did manage to pull it off.
More often than not though, it just ensured you received a booking for simulation. Moreover, it was removed in subsequent editions as EA did not want to condone diving.
However, a more realistic version of it could be introduced in FIFA 20. Imagine what success the likes of Neymar and Mohamed Salah would enjoy with such a feature in the game.