What speech disorder is this?

Like today when I was playing Rugby i said to my friend, " She has an a.ss full of face," instead of she has a face full of a.ss. Other time I've done stuff like diary dear (which is the one me and my friends laugh about the most xD), she has a man like a voice and one time where I went my tables has loads of tables! (instead of my book has loads of tables). Could anyone tell me what it is? It doesn't really bother me, I just laugh it off and find it usual with me. Any ideas why I do this too? I'm 13 and I mainly put it to being tired a lot but I want to know if there is anything else that could contribute to it? Thanks :)