I don't generally have thoughts about tickling other guys ('cept in roleplay sometimes, or given certain "fantasy" scenarios, like interrogations kidnappings or whatnot), but I've encountered a few friends and acquaintances who could be considered "cute" in general (by mannerisms and personality) who at times acted "so cute" about something that thoughts of pouncing and tickling did come to mind. :lol Like those, "oh my God that is so adorable!" moments that occur regardless of gender. x)
The trigger for me tends to be the guy's attire, in addition to attitude - if his feet are really cute and well-cared for, or the socks he's wearing are squee-worthy. I don't get "dream scenarios" about those guys, rather improvised "I kinda wanna get him!" thoughts that flash by the mind. xD