try this

Code:
alias floodcheck {
  var %fl.time = 10, %fl.lines = 3, %fl.ignore = 5
  inc $iif(!$($+(%,flood,.,$1,.,$2),2),$+(-eu,%fl.time)) $+(%,flood,.,$1,.,$2)
  if ( $($+(%,flood,.,$1,.,$2),2) >= %fl.lines ) .ignore $+(-u,$calc(%fl.ignore * 60)) $2
}


Syntax: floodcheck $cid $nick

Sample use for the alias:

Code:
 On *:TEXT:@test:#: {
 floodcheck $cid $nick
 msg $chan this is a test
}


When the snippet detects the flood, it ignores the nick for 5 mins. Default flood value is 3 lines within 10 secs. Change the value in the variables to fit your needs.