Funny Dirty Joke

Girl: You're stupid!
Boy:No I'm not!
Girl: okay then sing the alphabet!
Boy Ok here it is a,b,c,e,f,g,h,I,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z. Done!
Girl: you missed out a letter!
Boy: I know I'll give you the d later...