Eggsy can't help but laugh just a touch at Harry's comment before he leans up to kiss him again. While he does that, his hands move down, working at Harry's shirt to untuck it from his trousers, figuring that's the easiest way to get hands on skin without fumbling with buttons (though eventually he'll have to). He's not entirely inexperienced at this, but he lacks finesse here that he'd have fighting or free running or any of that.