There are many kinds of alternative swearwords, they are used for many reasons ranging from you don't want to get in trouble to you wanna look cool in front of your friends. Some examples: (note to add "er" or "ing" or whatever on the end use appropiate)
Fuck = Funk
Shit = Shnizz, Shizz, Shnizzle
Dick = Dink
Twat = Twit
Piss = Wizz
Those are some free tasters! Make you're own up!
Examples of alternative swearwords being used in day to day life:
"Funk you, you funking piece of shnizz!"
"You funker! How could you be so stupid!"
"Go suck Jerry's dink you funking fag!"
"Ah ya twit!"
"Wizz off moron!"
"Oh yeah I'm down with the shnizzle!"