HELP QUICK!

Okay so my boyfriend is coming over in maybe an hour and he's asked me to give him sloppy head.. the thing about that is i don't like being messy!! lol i'll suck his dick all nice and all but i won't do anything else so can someone give me some tips on how to get me going with this?? he just told me he wanted it sloppy so i'm willing to try. please help lmao i want to please him