During play during single player mode Hold [Ctrl] + [Alt] + [Shift] + [F7] until a prompt appears. Now enter one of these cheats:

No damage(Scores will be disabled) /nodamage
Enable damage /damage
Sky spins /dizzy
Toggle police radar(Scores will be disabled) /fuzz
Bridge very quickly(Scores will be disabled) /bridge
Airplanes becomes UFOs /ufo
Train becomes line of airplanes /swap
Cars in traffic have no friction(Scores will be disabled) /slide
Player's car has no friction(Scores will be disabled) /puck
Low gravity(Scores will be disabled) /grav
Use horn to shoot mailboxes(Scores will be disabled) /postal
Fast commentary /talkfast
Slow commentary /talkslow
Large people /big
Small people /tiny
Disable smoking tires /nosmoke
Enable smoking tires /smoke