I have to go home.

I can sing that song so much better.

I have to take my pet to the emergency vet clinic

I'm a friend of _________and he/she said I can sing next
anytime I want (used a lot when a "sub" host is running
the regular KJ's show).

My girlfriend is awesome - let her sing next.

I'm leaving in 10 minutes.

I have to go to work in the morning.

It's _______'s birthday - please let them sing.

I have to leave for another karaoke show.

I own this place.

The club owner said I could.

 I need to sing now so I can start drinking.

 I have finally had enough to drink and I have to sing before
I get too drunk.

My friends dared me and if I don't sing now, I never will.

I have to catch a plane.

My manager (or a talent agent) is in the audience and wants
to hear me sing!

I'm drunk and I don't know what I'm doing.

I spend a lot of money in this club.

If I don't sing next, I'm going to the club down and the street
and taking all of my friends with me.

My relatives are in town visiting and they're leaving to go
back home tomorrow.

I'll give you a tip!

I have to take someone to the emergency room

I signed-up hours ago and you haven't called me up yet.

I signed-up last night and you never called me up to sing.

We're all here together and we want to sing "Love Shack".

I have to go to church tomorrow. (usually heard on Saturday nights) 

I'm trying to get this girl's/guy's attention and want to
impress them with my singing.

I'm old and can't stay up any later.

Nobody will know.