What is how do guys react when they see a pretty girl?

Reactions can vary widely depending on the individual, their personality, cultural background, and the social context. Here are some common reactions that some people might have when they see someone they find attractive:

1. Visual Cues: Some might find it difficult not to look at the person, and they may glance more often or try to make eye contact.

2. Body Language: Changes might include standing up straighter, puffing up the chest, or other signs of trying to appear more confident or attractive.

3. Nervousness: Some might become more self-conscious or display signs of nervousness, such as fidgeting, blushing, or avoiding direct eye contact initially.

4. Initiating Interaction: They might attempt to start a conversation or engage in social interaction, whether directly with the person they find attractive or by joining the group they are in.

5. Behavioral Changes: There might be an effort to show off, tell jokes, or otherwise engage in behaviors intended to impress.

6. Silence or Shyness: Conversely, some might become more reserved or shy when confronted with someone they deem attractive.

7. Increased Friendliness: Some might become more polite, attentive, or helpful to the person of interest.

8. Verbal Compliments: Expressing admiration directly through compliments, though the appropriateness of this can depend on the context and the relationship.

Each reaction is also influenced by personal and social factors, such as self-esteem, previous experiences, interpersonal skills, and the norms of the setting they are in. It's important to note that everyone is different, and reactions can range from overt to very subtle.