Go to "Options", then "Keyboard", then "Advanced". Check the "Developers Console" option. Press ~ during game play to display the console window. Enter one of the following codes:
Effect - Code
Free bomb, as terrorist - buy c4
Set gravity - sv_gravity [number]
$16,000 - impulse 101
Getting onto tall boxes without boost
Buy a frag grenade and stand next to the box that you want to get on. Throw the grenade opposite the box from you onto the floor. Jump, press against the box, and you will be boosted very high. If timed correctly you can get yourself on the box at a cost of 40 HP.
Noclip
Press ~ during playing to activate console. Then write NOCLIP. You'll be able to walk in the air and move through buildings! (Note: in order for the cheat to work, sv_cheats must be turned to 1)
Thirdperson in CSS!
As you all maybe don't know what thirdperson is, I will explain short. Thirdperson is when you can see your full character. First person (when you only see your hands and gun). Here comes the point. Start CSS normally and click 'create new server'. choose any random map and SPECTATE when you join. Open up the console and write 'sv_cheats 1' then you write 'bot_stop' (afftecting the bots so they won't move anywhere, only duck) and join. write in your console 'thirdperson' and you will see something pretty amazing. Leave the bot-server and join your favorite servers. It's not so easy to control your aiming when you're in this state, because you've been playing with hands and gun from the beginning. Have fun, smile and kill some noobs!